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* mm/page_alloc: fix the page address of higher page's buddy calculationLi Haifeng2012-09-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | The heuristic method for buddy has been introduced since commit 43506fad21ca ("mm/page_alloc.c: simplify calculation of combined index of adjacent buddy lists"). But the page address of higher page's buddy was wrongly calculated, which will lead page_is_buddy to fail for ever. IOW, the heuristic method would be disabled with the wrong page address of higher page's buddy. Calculating the page address of higher page's buddy should be based higher_page with the offset between index of higher page and index of higher page's buddy. Signed-off-by: Haifeng Li <omycle@gmail.com> Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KyongHo Cho <pullip.cho@samsung.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: <stable@vger.kernel.org> [2.6.38+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: compaction: Abort async compaction if locks are contended or taking too longMel Gorman2012-08-211-6/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Jim Schutt reported a problem that pointed at compaction contending heavily on locks. The workload is straight-forward and in his own words; The systems in question have 24 SAS drives spread across 3 HBAs, running 24 Ceph OSD instances, one per drive. FWIW these servers are dual-socket Intel 5675 Xeons w/48 GB memory. I've got ~160 Ceph Linux clients doing dd simultaneously to a Ceph file system backed by 12 of these servers. Early in the test everything looks fine procs -------------------memory------------------ ---swap-- -----io---- --system-- -----cpu------- r b swpd free buff cache si so bi bo in cs us sy id wa st 31 15 0 287216 576 38606628 0 0 2 1158 2 14 1 3 95 0 0 27 15 0 225288 576 38583384 0 0 18 2222016 203357 134876 11 56 17 15 0 28 17 0 219256 576 38544736 0 0 11 2305932 203141 146296 11 49 23 17 0 6 18 0 215596 576 38552872 0 0 7 2363207 215264 166502 12 45 22 20 0 22 18 0 226984 576 38596404 0 0 3 2445741 223114 179527 12 43 23 22 0 and then it goes to pot procs -------------------memory------------------ ---swap-- -----io---- --system-- -----cpu------- r b swpd free buff cache si so bi bo in cs us sy id wa st 163 8 0 464308 576 36791368 0 0 11 22210 866 536 3 13 79 4 0 207 14 0 917752 576 36181928 0 0 712 1345376 134598 47367 7 90 1 2 0 123 12 0 685516 576 36296148 0 0 429 1386615 158494 60077 8 84 5 3 0 123 12 0 598572 576 36333728 0 0 1107 1233281 147542 62351 7 84 5 4 0 622 7 0 660768 576 36118264 0 0 557 1345548 151394 59353 7 85 4 3 0 223 11 0 283960 576 36463868 0 0 46 1107160 121846 33006 6 93 1 1 0 Note that system CPU usage is very high blocks being written out has dropped by 42%. He analysed this with perf and found perf record -g -a sleep 10 perf report --sort symbol --call-graph fractal,5 34.63% [k] _raw_spin_lock_irqsave | |--97.30%-- isolate_freepages | compaction_alloc | unmap_and_move | migrate_pages | compact_zone | compact_zone_order | try_to_compact_pages | __alloc_pages_direct_compact | __alloc_pages_slowpath | __alloc_pages_nodemask | alloc_pages_vma | do_huge_pmd_anonymous_page | handle_mm_fault | do_page_fault | page_fault | | | |--87.39%-- skb_copy_datagram_iovec | | tcp_recvmsg | | inet_recvmsg | | sock_recvmsg | | sys_recvfrom | | system_call | | __recv | | | | | --100.00%-- (nil) | | | --12.61%-- memcpy --2.70%-- [...] There was other data but primarily it is all showing that compaction is contended heavily on the zone->lock and zone->lru_lock. commit [b2eef8c0: mm: compaction: minimise the time IRQs are disabled while isolating pages for migration] noted that it was possible for migration to hold the lru_lock for an excessive amount of time. Very broadly speaking this patch expands the concept. This patch introduces compact_checklock_irqsave() to check if a lock is contended or the process needs to be scheduled. If either condition is true then async compaction is aborted and the caller is informed. The page allocator will fail a THP allocation if compaction failed due to contention. This patch also introduces compact_trylock_irqsave() which will acquire the lock only if it is not contended and the process does not need to schedule. Reported-by: Jim Schutt <jaschut@sandia.gov> Tested-by: Jim Schutt <jaschut@sandia.gov> Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: correct page->pfmemalloc to fix deactivate_slab regressionAlex Shi2012-08-211-10/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit cfd19c5a9ecf ("mm: only set page->pfmemalloc when ALLOC_NO_WATERMARKS was used") tried to narrow down page->pfmemalloc setting, but it missed some places the pfmemalloc should be set. So, in __slab_alloc, the unalignment pfmemalloc and ALLOC_NO_WATERMARKS cause incorrect deactivate_slab() on our core2 server: 64.73% fio [kernel.kallsyms] [k] _raw_spin_lock | --- _raw_spin_lock | |---0.34%-- deactivate_slab | __slab_alloc | kmem_cache_alloc | | That causes our fio sync write performance to have a 40% regression. Move the checking in get_page_from_freelist() which resolves this issue. Signed-off-by: Alex Shi <alex.shi@intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Eric Dumazet <eric.dumazet@gmail.com> Tested-by: Sage Weil <sage@inktank.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove node_start_pfn checking in new WARN_ON for nowLinus Torvalds2012-08-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Borislav Petkov reports that the new warning added in commit 88fdf75d1bb5 ("mm: warn if pg_data_t isn't initialized with zero") triggers for him, and it is the node_start_pfn field that has already been initialized once. The call trace looks like this: x86_64_start_kernel -> x86_64_start_reservations -> start_kernel -> setup_arch -> paging_init -> zone_sizes_init -> free_area_init_nodes -> free_area_init_node and (with the warning replaced by debug output), Borislav sees On node 0 totalpages: 4193848 DMA zone: 64 pages used for memmap DMA zone: 6 pages reserved DMA zone: 3890 pages, LIFO batch:0 DMA32 zone: 16320 pages used for memmap DMA32 zone: 798464 pages, LIFO batch:31 Normal zone: 52736 pages used for memmap Normal zone: 3322368 pages, LIFO batch:31 free_area_init_node: pgdat->node_start_pfn: 4423680 <---- On node 1 totalpages: 4194304 Normal zone: 65536 pages used for memmap Normal zone: 4128768 pages, LIFO batch:31 free_area_init_node: pgdat->node_start_pfn: 8617984 <---- On node 2 totalpages: 4194304 Normal zone: 65536 pages used for memmap Normal zone: 4128768 pages, LIFO batch:31 free_area_init_node: pgdat->node_start_pfn: 12812288 <---- On node 3 totalpages: 4194304 Normal zone: 65536 pages used for memmap Normal zone: 4128768 pages, LIFO batch:31 so remove the bogus warning for now to avoid annoying people. Minchan Kim is looking at it. Reported-by: Borislav Petkov <bp@amd64.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove redundant initializationMinchan Kim2012-07-311-7/+2
| | | | | | | | | | | pg_data_t is zeroed before reaching free_area_init_core(), so remove the now unnecessary initializations. Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: warn if pg_data_t isn't initialized with zeroMinchan Kim2012-07-311-0/+3
| | | | | | | | | | | | | | | | | | | | | Warn if memory-hotplug/boot code doesn't initialize pg_data_t with zero when it is allocated. Arch code and memory hotplug already initiailize pg_data_t. So this warning should never happen. I select fields randomly near the beginning, middle and end of pg_data_t for checking. This patch isn't for performance but for removing initialization code which is necessary to add whenever we adds new field to pg_data_t or zone. Firstly, Andrew suggested clearing out of pg_data_t in MM core part but Tejun doesn't like it because in the future, some archs can initialize some fields in arch code and pass them into general MM part so blindly clearing it out in mm core part would be very annoying. Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is ↵Mel Gorman2012-07-311-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | backed by network storage If swap is backed by network storage such as NBD, there is a risk that a large number of reclaimers can hang the system by consuming all PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune min_free_kbytes in advance which is a bit fragile. This patch throttles direct reclaimers if half the PF_MEMALLOC reserves are in use. If the system is routinely getting throttled the system administrator can increase min_free_kbytes so degradation is smoother but the system will keep running. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: ignore mempolicies when using ALLOC_NO_WATERMARKMel Gorman2012-07-311-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The reserve is proportionally distributed over all !highmem zones in the system. So we need to allow an emergency allocation access to all zones. In order to do that we need to break out of any mempolicy boundaries we might have. In my opinion that does not break mempolicies as those are user oriented and not system oriented. That is, system allocations are not guaranteed to be within mempolicy boundaries. For instance IRQs do not even have a mempolicy. So breaking out of mempolicy boundaries for 'rare' emergency allocations, which are always system allocations (as opposed to user) is ok. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: only set page->pfmemalloc when ALLOC_NO_WATERMARKS was usedMel Gorman2012-07-311-13/+14
| | | | | | | | | | | | | | | | | | | | | | | | | __alloc_pages_slowpath() is called when the number of free pages is below the low watermark. If the caller is entitled to use ALLOC_NO_WATERMARKS then the page will be marked page->pfmemalloc. This protects more pages than are strictly necessary as we only need to protect pages allocated below the min watermark (the pfmemalloc reserves). This patch only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was required to allocate the page. [rientjes@google.com: David noticed the problem during review] Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: allow PF_MEMALLOC from softirq contextMel Gorman2012-07-311-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is needed to allow network softirq packet processing to make use of PF_MEMALLOC. Currently softirq context cannot use PF_MEMALLOC due to it not being associated with a task, and therefore not having task flags to fiddle with - thus the gfp to alloc flag mapping ignores the task flags when in interrupts (hard or soft) context. Allowing softirqs to make use of PF_MEMALLOC therefore requires some trickery. This patch borrows the task flags from whatever process happens to be preempted by the softirq. It then modifies the gfp to alloc flags mapping to not exclude task flags in softirq context, and modify the softirq code to save, clear and restore the PF_MEMALLOC flag. The save and clear, ensures the preempted task's PF_MEMALLOC flag doesn't leak into the softirq. The restore ensures a softirq's PF_MEMALLOC flag cannot leak back into the preempted process. This should be safe due to the following reasons Softirqs can run on multiple CPUs sure but the same task should not be executing the same softirq code. Neither should the softirq handler be preempted by any other softirq handler so the flags should not leak to an unrelated softirq. Softirqs re-enable hardware interrupts in __do_softirq() so can be preempted by hardware interrupts so PF_MEMALLOC is inherited by the hard IRQ. However, this is similar to a process in reclaim being preempted by a hardirq. While PF_MEMALLOC is set, gfp_to_alloc_flags() distinguishes between hard and soft irqs and avoids giving a hardirq the ALLOC_NO_WATERMARKS flag. If the softirq is deferred to ksoftirq then its flags may be used instead of a normal tasks but as the softirq cannot be preempted, the PF_MEMALLOC flag does not leak to other code by accident. [davem@davemloft.net: Document why PF_MEMALLOC is safe] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce __GFP_MEMALLOC to allow access to emergency reservesMel Gorman2012-07-311-12/+10
| | | | | | | | | | | | | | | | | | | | | | __GFP_MEMALLOC will allow the allocation to disregard the watermarks, much like PF_MEMALLOC. It allows one to pass along the memalloc state in object related allocation flags as opposed to task related flags, such as sk->sk_allocation. This removes the need for ALLOC_PFMEMALLOC as callers using __GFP_MEMALLOC can get the ALLOC_NO_WATERMARK flag which is now enough to identify allocations related to page reclaim. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: sl[au]b: add knowledge of PFMEMALLOC reserve pagesMel Gorman2012-07-311-5/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a user or administrator requires swap for their application, they create a swap partition and file, format it with mkswap and activate it with swapon. Swap over the network is considered as an option in diskless systems. The two likely scenarios are when blade servers are used as part of a cluster where the form factor or maintenance costs do not allow the use of disks and thin clients. The Linux Terminal Server Project recommends the use of the Network Block Device (NBD) for swap according to the manual at https://sourceforge.net/projects/ltsp/files/Docs-Admin-Guide/LTSPManual.pdf/download There is also documentation and tutorials on how to setup swap over NBD at places like https://help.ubuntu.com/community/UbuntuLTSP/EnableNBDSWAP The nbd-client also documents the use of NBD as swap. Despite this, the fact is that a machine using NBD for swap can deadlock within minutes if swap is used intensively. This patch series addresses the problem. The core issue is that network block devices do not use mempools like normal block devices do. As the host cannot control where they receive packets from, they cannot reliably work out in advance how much memory they might need. Some years ago, Peter Zijlstra developed a series of patches that supported swap over an NFS that at least one distribution is carrying within their kernels. This patch series borrows very heavily from Peter's work to support swapping over NBD as a pre-requisite to supporting swap-over-NFS. The bulk of the complexity is concerned with preserving memory that is allocated from the PFMEMALLOC reserves for use by the network layer which is needed for both NBD and NFS. Patch 1 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to preserve access to pages allocated under low memory situations to callers that are freeing memory. Patch 2 optimises the SLUB fast path to avoid pfmemalloc checks Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC reserves without setting PFMEMALLOC. Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves for later use by network packet processing. Patch 5 only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was required Patch 6 ignores memory policies when ALLOC_NO_WATERMARKS is set. Patches 7-12 allows network processing to use PFMEMALLOC reserves when the socket has been marked as being used by the VM to clean pages. If packets are received and stored in pages that were allocated under low-memory situations and are unrelated to the VM, the packets are dropped. Patch 11 reintroduces __skb_alloc_page which the networking folk may object to but is needed in some cases to propogate pfmemalloc from a newly allocated page to an skb. If there is a strong objection, this patch can be dropped with the impact being that swap-over-network will be slower in some cases but it should not fail. Patch 13 is a micro-optimisation to avoid a function call in the common case. Patch 14 tags NBD sockets as being SOCK_MEMALLOC so they can use PFMEMALLOC if necessary. Patch 15 notes that it is still possible for the PFMEMALLOC reserve to be depleted. To prevent this, direct reclaimers get throttled on a waitqueue if 50% of the PFMEMALLOC reserves are depleted. It is expected that kswapd and the direct reclaimers already running will clean enough pages for the low watermark to be reached and the throttled processes are woken up. Patch 16 adds a statistic to track how often processes get throttled Some basic performance testing was run using kernel builds, netperf on loopback for UDP and TCP, hackbench (pipes and sockets), iozone and sysbench. Each of them were expected to use the sl*b allocators reasonably heavily but there did not appear to be significant performance variances. For testing swap-over-NBD, a machine was booted with 2G of RAM with a swapfile backed by NBD. 8*NUM_CPU processes were started that create anonymous memory mappings and read them linearly in a loop. The total size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under memory pressure. Without the patches and using SLUB, the machine locks up within minutes and runs to completion with them applied. With SLAB, the story is different as an unpatched kernel run to completion. However, the patched kernel completed the test 45% faster. MICRO 3.5.0-rc2 3.5.0-rc2 vanilla swapnbd Unrecognised test vmscan-anon-mmap-write MMTests Statistics: duration Sys Time Running Test (seconds) 197.80 173.07 User+Sys Time Running Test (seconds) 206.96 182.03 Total Elapsed Time (seconds) 3240.70 1762.09 This patch: mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages Allocations of pages below the min watermark run a risk of the machine hanging due to a lack of memory. To prevent this, only callers who have PF_MEMALLOC or TIF_MEMDIE set and are not processing an interrupt are allowed to allocate with ALLOC_NO_WATERMARKS. Once they are allocated to a slab though, nothing prevents other callers consuming free objects within those slabs. This patch limits access to slab pages that were alloced from the PFMEMALLOC reserves. When this patch is applied, pages allocated from below the low watermark are returned with page->pfmemalloc set and it is up to the caller to determine how the page should be protected. SLAB restricts access to any page with page->pfmemalloc set to callers which are known to able to access the PFMEMALLOC reserve. If one is not available, an attempt is made to allocate a new page rather than use a reserve. SLUB is a bit more relaxed in that it only records if the current per-CPU page was allocated from PFMEMALLOC reserve and uses another partial slab if the caller does not have the necessary GFP or process flags. This was found to be sufficient in tests to avoid hangs due to SLUB generally maintaining smaller lists than SLAB. In low-memory conditions it does mean that !PFMEMALLOC allocators can fail a slab allocation even though free objects are available because they are being preserved for callers that are freeing pages. [a.p.zijlstra@chello.nl: Original implementation] [sebastian@breakpoint.cc: Correct order of page flag clearing] Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memory-hotplug: fix kswapd looping forever problemMinchan Kim2012-07-311-0/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When hotplug offlining happens on zone A, it starts to mark freed page as MIGRATE_ISOLATE type in buddy for preventing further allocation. (MIGRATE_ISOLATE is very irony type because it's apparently on buddy but we can't allocate them). When the memory shortage happens during hotplug offlining, current task starts to reclaim, then wake up kswapd. Kswapd checks watermark, then go sleep because current zone_watermark_ok_safe doesn't consider MIGRATE_ISOLATE freed page count. Current task continue to reclaim in direct reclaim path without kswapd's helping. The problem is that zone->all_unreclaimable is set by only kswapd so that current task would be looping forever like below. __alloc_pages_slowpath restart: wake_all_kswapd rebalance: __alloc_pages_direct_reclaim do_try_to_free_pages if global_reclaim && !all_unreclaimable return 1; /* It means we did did_some_progress */ skip __alloc_pages_may_oom should_alloc_retry goto rebalance; If we apply KOSAKI's patch[1] which doesn't depends on kswapd about setting zone->all_unreclaimable, we can solve this problem by killing some task in direct reclaim path. But it doesn't wake up kswapd, still. It could be a problem still if other subsystem needs GFP_ATOMIC request. So kswapd should consider MIGRATE_ISOLATE when it calculate free pages BEFORE going sleep. This patch counts the number of MIGRATE_ISOLATE page block and zone_watermark_ok_safe will consider it if the system has such blocks (fortunately, it's very rare so no problem in POV overhead and kswapd is never hotpath). Copy/modify from Mel's quote " Ideal solution would be "allocating" the pageblock. It would keep the free space accounting as it is but historically, memory hotplug didn't allocate pages because it would be difficult to detect if a pageblock was isolated or if part of some balloon. Allocating just full pageblocks would work around this, However, it would play very badly with CMA. " [1] http://lkml.org/lkml/2012/6/14/74 [akpm@linux-foundation.org: simplify nr_zone_isolate_freepages(), rework zone_watermark_ok_safe() comment, simplify set_pageblock_isolate() and restore_pageblock_isolate()] [akpm@linux-foundation.org: fix CONFIG_MEMORY_ISOLATION=n build] Signed-off-by: Minchan Kim <minchan@kernel.org> Suggested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Tested-by: Aaditya Kumar <aaditya.kumar.30@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix free page check in zone_watermark_ok()Minchan Kim2012-07-311-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | __zone_watermark_ok currently compares free_pages which is a signed type with z->lowmem_reserve[classzone_idx] which is unsigned which might lead to sign overflow if free_pages doesn't satisfy the given order (or it came as negative already) and then we rely on the following order loop to fix it (which doesn't work for order-0). Let's fix the type conversion and do not rely on the given value of free_pages or follow up fixups. This patch fixes it because "memory-hotplug: fix kswapd looping forever problem" depends on this. As benefit of this patch, it doesn't rely on the loop to exit __zone_watermark_ok in case of high order check and make the first test effective.(ie, if (free_pages <= min + lowmem_reserve)) Aaditya reported this problem when he test my hotplug patch. Reported-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com> Tested-by: Aaditya Kumar <aaditya.kumar@ap.sony.com> Signed-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: factor out memory isolate functionsMinchan Kim2012-07-311-76/+4
| | | | | | | | | | | | | | | | | | mm/page_alloc.c has some memory isolation functions but they are used only when we enable CONFIG_{CMA|MEMORY_HOTPLUG|MEMORY_FAILURE}. So let's make it configurable by new CONFIG_MEMORY_ISOLATION so that it can reduce binary size and we can check it simple by CONFIG_MEMORY_ISOLATION, not if defined CONFIG_{CMA|MEMORY_HOTPLUG|MEMORY_FAILURE}. Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Andi Kleen <andi@firstfloor.org> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hotplug: mark memory hotplug code in page_alloc.c as __meminitJiang Liu2012-07-311-32/+34
| | | | | | | | | | | | | | | | | | | | | | | Mark functions used by both boot and memory hotplug as __meminit to reduce memory footprint when memory hotplug is disabled. Alos guard zone_pcp_update() with CONFIG_MEMORY_HOTPLUG because it's only used by memory hotplug code. Signed-off-by: Jiang Liu <liuj97@gmail.com> Cc: Wei Wang <Bessel.Wang@huawei.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Keping Chen <chenkeping@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hotplug: free zone->pageset when a zone becomes emptyJiang Liu2012-07-311-0/+13
| | | | | | | | | | | | | | | | | | | | | | When a zone becomes empty after memory offlining, free zone->pageset. Otherwise it will cause memory leak when adding memory to the empty zone again because build_all_zonelists() will allocate zone->pageset for an empty zone. Signed-off-by: Jiang Liu <liuj97@gmail.com> Signed-off-by: Wei Wang <Bessel.Wang@huawei.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Keping Chen <chenkeping@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hotplug: correctly setup fallback zonelists when creating new pgdatJiang Liu2012-07-311-5/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When hotadd_new_pgdat() is called to create new pgdat for a new node, a fallback zonelist should be created for the new node. There's code to try to achieve that in hotadd_new_pgdat() as below: /* * The node we allocated has no zone fallback lists. For avoiding * to access not-initialized zonelist, build here. */ mutex_lock(&zonelists_mutex); build_all_zonelists(pgdat, NULL); mutex_unlock(&zonelists_mutex); But it doesn't work as expected. When hotadd_new_pgdat() is called, the new node is still in offline state because node_set_online(nid) hasn't been called yet. And build_all_zonelists() only builds zonelists for online nodes as: for_each_online_node(nid) { pg_data_t *pgdat = NODE_DATA(nid); build_zonelists(pgdat); build_zonelist_cache(pgdat); } Though we hope to create zonelist for the new pgdat, but it doesn't. So add a new parameter "pgdat" the build_all_zonelists() to build pgdat for the new pgdat too. Signed-off-by: Jiang Liu <liuj97@gmail.com> Signed-off-by: Xishi Qiu <qiuxishi@huawei.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Keping Chen <chenkeping@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: setup pageblock_order before it's used by sparsememXishi Qiu2012-07-311-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On architectures with CONFIG_HUGETLB_PAGE_SIZE_VARIABLE set, such as Itanium, pageblock_order is a variable with default value of 0. It's set to the right value by set_pageblock_order() in function free_area_init_core(). But pageblock_order may be used by sparse_init() before free_area_init_core() is called along path: sparse_init() ->sparse_early_usemaps_alloc_node() ->usemap_size() ->SECTION_BLOCKFLAGS_BITS ->((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS) The uninitialized pageblock_size will cause memory wasting because usemap_size() returns a much bigger value then it's really needed. For example, on an Itanium platform, sparse_init() pageblock_order=0 usemap_size=24576 free_area_init_core() before pageblock_order=0, usemap_size=24576 free_area_init_core() after pageblock_order=12, usemap_size=8 That means 24K memory has been wasted for each section, so fix it by calling set_pageblock_order() from sparse_init(). Signed-off-by: Xishi Qiu <qiuxishi@huawei.com> Signed-off-by: Jiang Liu <liuj97@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Keping Chen <chenkeping@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: have order > 0 compaction start off where it leftRik van Riel2012-07-311-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Order > 0 compaction stops when enough free pages of the correct page order have been coalesced. When doing subsequent higher order allocations, it is possible for compaction to be invoked many times. However, the compaction code always starts out looking for things to compact at the start of the zone, and for free pages to compact things to at the end of the zone. This can cause quadratic behaviour, with isolate_freepages starting at the end of the zone each time, even though previous invocations of the compaction code already filled up all free memory on that end of the zone. This can cause isolate_freepages to take enormous amounts of CPU with certain workloads on larger memory systems. The obvious solution is to have isolate_freepages remember where it left off last time, and continue at that point the next time it gets invoked for an order > 0 compaction. This could cause compaction to fail if cc->free_pfn and cc->migrate_pfn are close together initially, in that case we restart from the end of the zone and try once more. Forced full (order == -1) compactions are left alone. [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: s/laste/last/, use 80 cols] Signed-off-by: Rik van Riel <riel@redhat.com> Reported-by: Jim Schutt <jaschut@sandia.gov> Tested-by: Jim Schutt <jaschut@sandia.gov> Cc: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: clean up __count_immobile_pages()Minchan Kim2012-07-311-16/+18
| | | | | | | | | | | | | | The __count_immobile_pages() naming is rather awkward. Choose a more clear name and add a comment. Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: do not use page_count() without a page pinMinchan Kim2012-07-311-1/+8
| | | | | | | | | | | | | | | | | | | | | d179e84ba ("mm: vmscan: do not use page_count without a page pin") fixed this problem in vmscan.c but same problem is in __count_immobile_pages(). I copy and paste d179e84ba's contents for description. "It is unsafe to run page_count during the physical pfn scan because compound_head could trip on a dangling pointer when reading page->first_page if the compound page is being freed by another CPU." Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Wanpeng Li <liwp.linux@gmail.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: clear pages_scanned only if draining a pcp adds pages to the buddy ↵KOSAKI Motohiro2012-07-311-3/+6
| | | | | | | | | | | | | | | | | | | | | allocator again commit 2ff754fa8f ("mm: clear pages_scanned only if draining a pcp adds pages to the buddy allocator again") fixed one free_pcppages_bulk() misuse. But two another miuse still exist. This patch fixes it. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Minchan Kim <minchan@kernel.org> Cc: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/buddy: cleanup on should_fail_alloc_pageGavin Shan2012-07-311-7/+7
| | | | | | | | | | | | | | Currently, function should_fail() has "bool" for its return value, so it's reasonable to change the return value of function should_fail_alloc_page() into "bool" as well. The patch does cleanup on function should_fail_alloc_page() to have "bool" for its return value. Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: cma: don't replace lowmem pages with highmemRabin Vincent2012-07-061-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The filesystem layer expects pages in the block device's mapping to not be in highmem (the mapping's gfp mask is set in bdget()), but CMA can currently replace lowmem pages with highmem pages, leading to crashes in filesystem code such as the one below: Unable to handle kernel NULL pointer dereference at virtual address 00000400 pgd = c0c98000 [00000400] *pgd=00c91831, *pte=00000000, *ppte=00000000 Internal error: Oops: 817 [#1] PREEMPT SMP ARM CPU: 0 Not tainted (3.5.0-rc5+ #80) PC is at __memzero+0x24/0x80 ... Process fsstress (pid: 323, stack limit = 0xc0cbc2f0) Backtrace: [<c010e3f0>] (ext4_getblk+0x0/0x180) from [<c010e58c>] (ext4_bread+0x1c/0x98) [<c010e570>] (ext4_bread+0x0/0x98) from [<c0117944>] (ext4_mkdir+0x160/0x3bc) r4:c15337f0 [<c01177e4>] (ext4_mkdir+0x0/0x3bc) from [<c00c29e0>] (vfs_mkdir+0x8c/0x98) [<c00c2954>] (vfs_mkdir+0x0/0x98) from [<c00c2a60>] (sys_mkdirat+0x74/0xac) r6:00000000 r5:c152eb40 r4:000001ff r3:c14b43f0 [<c00c29ec>] (sys_mkdirat+0x0/0xac) from [<c00c2ab8>] (sys_mkdir+0x20/0x24) r6:beccdcf0 r5:00074000 r4:beccdbbc [<c00c2a98>] (sys_mkdir+0x0/0x24) from [<c000e3c0>] (ret_fast_syscall+0x0/0x30) Fix this by replacing only highmem pages with highmem. Reported-by: Laura Abbott <lauraa@codeaurora.org> Signed-off-by: Rabin Vincent <rabin@rab.in> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
* Revert "mm: compaction: handle incorrect MIGRATE_UNMOVABLE type pageblocks"Linus Torvalds2012-06-031-4/+4
| | | | | | | | | | | | | | | | | | | | | | This reverts commit 5ceb9ce6fe9462a298bb2cd5c9f1ca6cb80a0199. That commit seems to be the cause of the mm compation list corruption issues that Dave Jones reported. The locking (or rather, absense there-of) is dubious, as is the use of the 'page' variable once it has been found to be outside the pageblock range. So revert it for now, we can re-visit this for 3.6. If we even need to: as Minchan Kim says, "The patch wasn't a bug fix and even test workload was very theoretical". Reported-and-tested-by: Dave Jones <davej@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add link from struct lruvec to struct zoneKonstantin Khlebnikov2012-05-291-7/+1
| | | | | | | | | | | | | | This is the first stage of struct mem_cgroup_zone removal. Further patches replace struct mem_cgroup_zone with a pointer to struct lruvec. If CONFIG_CGROUP_MEM_RES_CTLR=n lruvec_zone() is just container_of(). Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/memcg: move reclaim_stat into lruvecHugh Dickins2012-05-291-4/+4
| | | | | | | | | | | | | | | | | | | | | With mem_cgroup_disabled() now explicit, it becomes clear that the zone_reclaim_stat structure actually belongs in lruvec, per-zone when memcg is disabled but per-memcg per-zone when it's enabled. We can delete mem_cgroup_get_reclaim_stat(), and change update_page_reclaim_stat() to update just the one set of stats, the one which get_scan_count() will actually use. Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Glauber Costa <glommer@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/page_alloc.c: cleanupsAndrew Morton2012-05-291-4/+3
| | | | | | | | | | | - make pageflag_names[] const - remove null termination of pageflag_names[] Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Gavin Shan <shangw@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: page_alloc: catch out-of-date list of page flag namesJohannes Weiner2012-05-291-0/+2
| | | | | | | | | | | String tables with names of enum items are always prone to go out of sync with the enums themselves. Ensure during compile time that the name table of page flags has the same size as the page flags enum. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Gavin Shan <shangw@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/buddy: dump PG_compound_lock page flagGavin Shan2012-05-291-0/+3
| | | | | | | | | | | | | | | | | The array pageflag_names[] does conversion from page flags into their corresponding names so that a meaningful representation of the corresponding page flag can be printed. This mechanism is used while dumping page frames. However, the array missed PG_compound_lock. So the PG_compound_lock page flag would be printed as a digital number instead of a meaningful string. The patch fixes that and prints "compound_lock" for the PG_compound_lock page flag. Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: compaction: handle incorrect MIGRATE_UNMOVABLE type pageblocksBartlomiej Zolnierkiewicz2012-05-291-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When MIGRATE_UNMOVABLE pages are freed from MIGRATE_UNMOVABLE type pageblock (and some MIGRATE_MOVABLE pages are left in it) waiting until an allocation takes ownership of the block may take too long. The type of the pageblock remains unchanged so the pageblock cannot be used as a migration target during compaction. Fix it by: * Adding enum compact_mode (COMPACT_ASYNC_[MOVABLE,UNMOVABLE], and COMPACT_SYNC) and then converting sync field in struct compact_control to use it. * Adding nr_pageblocks_skipped field to struct compact_control and tracking how many destination pageblocks were of MIGRATE_UNMOVABLE type. If COMPACT_ASYNC_MOVABLE mode compaction ran fully in try_to_compact_pages() (COMPACT_COMPLETE) it implies that there is not a suitable page for allocation. In this case then check how if there were enough MIGRATE_UNMOVABLE pageblocks to try a second pass in COMPACT_ASYNC_UNMOVABLE mode. * Scanning the MIGRATE_UNMOVABLE pageblocks (during COMPACT_SYNC and COMPACT_ASYNC_UNMOVABLE compaction modes) and building a count based on finding PageBuddy pages, page_count(page) == 0 or PageLRU pages. If all pages within the MIGRATE_UNMOVABLE pageblock are in one of those three sets change the whole pageblock type to MIGRATE_MOVABLE. My particular test case (on a ARM EXYNOS4 device with 512 MiB, which means 131072 standard 4KiB pages in 'Normal' zone) is to: - allocate 120000 pages for kernel's usage - free every second page (60000 pages) of memory just allocated - allocate and use 60000 pages from user space - free remaining 60000 pages of kernel memory (now we have fragmented memory occupied mostly by user space pages) - try to allocate 100 order-9 (2048 KiB) pages for kernel's usage The results: - with compaction disabled I get 11 successful allocations - with compaction enabled - 14 successful allocations - with this patch I'm able to get all 100 successful allocations NOTE: If we can make kswapd aware of order-0 request during compaction, we can enhance kswapd with changing mode to COMPACT_ASYNC_FULL (COMPACT_ASYNC_MOVABLE + COMPACT_ASYNC_UNMOVABLE). Please see the following thread: http://marc.info/?l=linux-mm&m=133552069417068&w=2 [minchan@kernel.org: minor cleanups] Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/page_alloc.c: remove pageblock_default_order()Andrew Morton2012-05-291-18/+15
| | | | | | | | | | | | | | | | | This has always been broken: one version takes an unsigned int and the other version takes no arguments. This bug was hidden because one version of set_pageblock_order() was a macro which doesn't evaluate its argument. Simplify it all and remove pageblock_default_order() altogether. Reported-by: rajman mekaco <rajman.mekaco@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: print physical addresses consistently with other parts of kernelBjorn Helgaas2012-05-291-8/+11
| | | | | | | | | | | | | | | | | | | | | Print physical address info in a style consistent with the %pR style used elsewhere in the kernel. For example: -Zone PFN ranges: +Zone ranges: - DMA32 0x00000010 -> 0x00100000 + DMA32 [mem 0x00010000-0xffffffff] - Normal 0x00100000 -> 0x01080000 + Normal [mem 0x100000000-0x107fffffff] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-linus' of ↵Linus Torvalds2012-05-251-46/+363
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.linaro.org/people/mszyprowski/linux-dma-mapping Pull CMA and ARM DMA-mapping updates from Marek Szyprowski: "These patches contain two major updates for DMA mapping subsystem (mainly for ARM architecture). First one is Contiguous Memory Allocator (CMA) which makes it possible for device drivers to allocate big contiguous chunks of memory after the system has booted. The main difference from the similar frameworks is the fact that CMA allows to transparently reuse the memory region reserved for the big chunk allocation as a system memory, so no memory is wasted when no big chunk is allocated. Once the alloc request is issued, the framework migrates system pages to create space for the required big chunk of physically contiguous memory. For more information one can refer to nice LWN articles: - 'A reworked contiguous memory allocator': http://lwn.net/Articles/447405/ - 'CMA and ARM': http://lwn.net/Articles/450286/ - 'A deep dive into CMA': http://lwn.net/Articles/486301/ - and the following thread with the patches and links to all previous versions: https://lkml.org/lkml/2012/4/3/204 The main client for this new framework is ARM DMA-mapping subsystem. The second part provides a complete redesign in ARM DMA-mapping subsystem. The core implementation has been changed to use common struct dma_map_ops based infrastructure with the recent updates for new dma attributes merged in v3.4-rc2. This allows to use more than one implementation of dma-mapping calls and change/select them on the struct device basis. The first client of this new infractructure is dmabounce implementation which has been completely cut out of the core, common code. The last patch of this redesign update introduces a new, experimental implementation of dma-mapping calls on top of generic IOMMU framework. This lets ARM sub-platform to transparently use IOMMU for DMA-mapping calls if one provides required IOMMU hardware. For more information please refer to the following thread: http://www.spinics.net/lists/arm-kernel/msg175729.html The last patch merges changes from both updates and provides a resolution for the conflicts which cannot be avoided when patches have been applied on the same files (mainly arch/arm/mm/dma-mapping.c)." Acked by Andrew Morton <akpm@linux-foundation.org>: "Yup, this one please. It's had much work, plenty of review and I think even Russell is happy with it." * 'for-linus' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping: (28 commits) ARM: dma-mapping: use PMD size for section unmap cma: fix migration mode ARM: integrate CMA with DMA-mapping subsystem X86: integrate CMA with DMA-mapping subsystem drivers: add Contiguous Memory Allocator mm: trigger page reclaim in alloc_contig_range() to stabilise watermarks mm: extract reclaim code from __alloc_pages_direct_reclaim() mm: Serialize access to min_free_kbytes mm: page_isolation: MIGRATE_CMA isolation functions added mm: mmzone: MIGRATE_CMA migration type added mm: page_alloc: change fallbacks array handling mm: page_alloc: introduce alloc_contig_range() mm: compaction: export some of the functions mm: compaction: introduce isolate_freepages_range() mm: compaction: introduce map_pages() mm: compaction: introduce isolate_migratepages_range() mm: page_alloc: remove trailing whitespace ARM: dma-mapping: add support for IOMMU mapper ARM: dma-mapping: use alloc, mmap, free from dma_ops ARM: dma-mapping: remove redundant code and do the cleanup ... Conflicts: arch/x86/include/asm/dma-mapping.h
| * cma: fix migration modeMinchan Kim2012-05-211-1/+1
| | | | | | | | | | | | | | | | | | | | __alloc_contig_migrate_range calls migrate_pages with wrong argument for migrate_mode. Fix it. Cc: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
| * mm: trigger page reclaim in alloc_contig_range() to stabilise watermarksMarek Szyprowski2012-05-211-0/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | alloc_contig_range() performs memory allocation so it also should keep track on keeping the correct level of memory watermarks. This commit adds a call to *_slowpath style reclaim to grab enough pages to make sure that the final collection of contiguous pages from freelists will not starve the system. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> CC: Michal Nazarewicz <mina86@mina86.com> Tested-by: Rob Clark <rob.clark@linaro.org> Tested-by: Ohad Ben-Cohen <ohad@wizery.com> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Tested-by: Robert Nelson <robertcnelson@gmail.com> Tested-by: Barry Song <Baohua.Song@csr.com>
| * mm: extract reclaim code from __alloc_pages_direct_reclaim()Marek Szyprowski2012-05-211-9/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch extracts common reclaim code from __alloc_pages_direct_reclaim() function to separate function: __perform_reclaim() which can be later used by alloc_contig_range(). Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Cc: Michal Nazarewicz <mina86@mina86.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Tested-by: Rob Clark <rob.clark@linaro.org> Tested-by: Ohad Ben-Cohen <ohad@wizery.com> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Tested-by: Robert Nelson <robertcnelson@gmail.com> Tested-by: Barry Song <Baohua.Song@csr.com>
| * mm: Serialize access to min_free_kbytesMel Gorman2012-05-211-8/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | There is a race between the min_free_kbytes sysctl, memory hotplug and transparent hugepage support enablement. Memory hotplug uses a zonelists_mutex to avoid a race when building zonelists. Reuse it to serialise watermark updates. [a.p.zijlstra@chello.nl: Older patch fixed the race with spinlock] Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: Barry Song <Baohua.Song@csr.com>
| * mm: page_isolation: MIGRATE_CMA isolation functions addedMichal Nazarewicz2012-05-211-6/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit changes various functions that change pages and pageblocks migrate type between MIGRATE_ISOLATE and MIGRATE_MOVABLE in such a way as to allow to work with MIGRATE_CMA migrate type. Signed-off-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: Rob Clark <rob.clark@linaro.org> Tested-by: Ohad Ben-Cohen <ohad@wizery.com> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Tested-by: Robert Nelson <robertcnelson@gmail.com> Tested-by: Barry Song <Baohua.Song@csr.com>
| * mm: mmzone: MIGRATE_CMA migration type addedMichal Nazarewicz2012-05-211-16/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The MIGRATE_CMA migration type has two main characteristics: (i) only movable pages can be allocated from MIGRATE_CMA pageblocks and (ii) page allocator will never change migration type of MIGRATE_CMA pageblocks. This guarantees (to some degree) that page in a MIGRATE_CMA page block can always be migrated somewhere else (unless there's no memory left in the system). It is designed to be used for allocating big chunks (eg. 10MiB) of physically contiguous memory. Once driver requests contiguous memory, pages from MIGRATE_CMA pageblocks may be migrated away to create a contiguous block. To minimise number of migrations, MIGRATE_CMA migration type is the last type tried when page allocator falls back to other migration types when requested. Signed-off-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: Rob Clark <rob.clark@linaro.org> Tested-by: Ohad Ben-Cohen <ohad@wizery.com> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Tested-by: Robert Nelson <robertcnelson@gmail.com> Tested-by: Barry Song <Baohua.Song@csr.com>
| * mm: page_alloc: change fallbacks array handlingMichal Nazarewicz2012-05-211-4/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds a row for MIGRATE_ISOLATE type to the fallbacks array which was missing from it. It also, changes the array traversal logic a little making MIGRATE_RESERVE an end marker. The letter change, removes the implicit MIGRATE_UNMOVABLE from the end of each row which was read by __rmqueue_fallback() function. Signed-off-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: Rob Clark <rob.clark@linaro.org> Tested-by: Ohad Ben-Cohen <ohad@wizery.com> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Tested-by: Robert Nelson <robertcnelson@gmail.com> Tested-by: Barry Song <Baohua.Song@csr.com>
| * mm: page_alloc: introduce alloc_contig_range()Michal Nazarewicz2012-05-211-0/+188
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds the alloc_contig_range() function which tries to allocate given range of pages. It tries to migrate all already allocated pages that fall in the range thus freeing them. Once all pages in the range are freed they are removed from the buddy system thus allocated for the caller to use. Signed-off-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: Rob Clark <rob.clark@linaro.org> Tested-by: Ohad Ben-Cohen <ohad@wizery.com> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Tested-by: Robert Nelson <robertcnelson@gmail.com> Tested-by: Barry Song <Baohua.Song@csr.com>
| * mm: page_alloc: remove trailing whitespaceMichal Nazarewicz2012-05-211-7/+7
| | | | | | | | | | | | Signed-off-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Mel Gorman <mel@csn.ul.ie>
* | Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds2012-05-241-2/+5
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull more networking updates from David Miller: "Ok, everything from here on out will be bug fixes." 1) One final sync of wireless and bluetooth stuff from John Linville. These changes have all been in his tree for more than a week, and therefore have had the necessary -next exposure. John was just away on a trip and didn't have a change to send the pull request until a day or two ago. 2) Put back some defines in user exposed header file areas that were removed during the tokenring purge. From Stephen Hemminger and Paul Gortmaker. 3) A bug fix for UDP hash table allocation got lost in the pile due to one of those "you got it.. no I've got it.." situations. :-) From Tim Bird. 4) SKB coalescing in TCP needs to have stricter checks, otherwise we'll try to coalesce overlapping frags and crash. Fix from Eric Dumazet. 5) RCU routing table lookups can race with free_fib_info(), causing crashes when we deref the device pointers in the route. Fix by releasing the net device in the RCU callback. From Yanmin Zhang. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (293 commits) tcp: take care of overlaps in tcp_try_coalesce() ipv4: fix the rcu race between free_fib_info and ip_route_output_slow mm: add a low limit to alloc_large_system_hash ipx: restore token ring define to include/linux/ipx.h if: restore token ring ARP type to header xen: do not disable netfront in dom0 phy/micrel: Fix ID of KSZ9021 mISDN: Add X-Tensions USB ISDN TA XC-525 gianfar:don't add FCB length to hard_header_len Bluetooth: Report proper error number in disconnection Bluetooth: Create flags for bt_sk() Bluetooth: report the right security level in getsockopt Bluetooth: Lock the L2CAP channel when sending Bluetooth: Restore locking semantics when looking up L2CAP channels Bluetooth: Fix a redundant and problematic incoming MTU check Bluetooth: Add support for Foxconn/Hon Hai AR5BBU22 0489:E03C Bluetooth: Fix EIR data generation for mgmt_device_found Bluetooth: Fix Inquiry with RSSI event mask Bluetooth: improve readability of l2cap_seq_list code Bluetooth: Fix skb length calculation ...
| * | mm: add a low limit to alloc_large_system_hashTim Bird2012-05-241-2/+5
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | UDP stack needs a minimum hash size value for proper operation and also uses alloc_large_system_hash() for proper NUMA distribution of its hash tables and automatic sizing depending on available system memory. On some low memory situations, udp_table_init() must ignore the alloc_large_system_hash() result and reallocs a bigger memory area. As we cannot easily free old hash table, we leak it and kmemleak can issue a warning. This patch adds a low limit parameter to alloc_large_system_hash() to solve this problem. We then specify UDP_HTABLE_SIZE_MIN for UDP/UDPLite hash table allocation. Reported-by: Mark Asselstine <mark.asselstine@windriver.com> Reported-by: Tim Bird <tim.bird@am.sony.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | Merge tag 'driver-core-3.5-rc1' of ↵Linus Torvalds2012-05-221-3/+3
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core updates from Greg Kroah-Hartman: "Here's the driver core, and other driver subsystems, pull request for the 3.5-rc1 merge window. Outside of a few minor driver core changes, we ended up with the following different subsystem and core changes as well, due to interdependancies on the driver core: - hyperv driver updates - drivers/memory being created and some drivers moved into it - extcon driver subsystem created out of the old Android staging switch driver code - dynamic debug updates - printk rework, and /dev/kmsg changes All of this has been tested in the linux-next releases for a few weeks with no reported problems. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>" Fix up conflicts in drivers/extcon/extcon-max8997.c where git noticed that a patch to the deleted drivers/misc/max8997-muic.c driver needs to be applied to this one. * tag 'driver-core-3.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (90 commits) uio_pdrv_genirq: get irq through platform resource if not set otherwise memory: tegra{20,30}-mc: Remove empty *_remove() printk() - isolate KERN_CONT users from ordinary complete lines sysfs: get rid of some lockdep false positives Drivers: hv: util: Properly handle version negotiations. Drivers: hv: Get rid of an unnecessary check in vmbus_prep_negotiate_resp() memory: tegra{20,30}-mc: Use dev_err_ratelimited() driver core: Add dev_*_ratelimited() family Driver Core: don't oops with unregistered driver in driver_find_device() printk() - restore prefix/timestamp printing for multi-newline strings printk: add stub for prepend_timestamp() ARM: tegra30: Make MC optional in Kconfig ARM: tegra20: Make MC optional in Kconfig ARM: tegra30: MC: Remove unnecessary BUG*() ARM: tegra20: MC: Remove unnecessary BUG*() printk: correctly align __log_buf ARM: tegra30: Add Tegra Memory Controller(MC) driver ARM: tegra20: Add Tegra Memory Controller(MC) driver printk() - restore timestamp printing at console output printk() - do not merge continuation lines of different threads ...
| * mm: use KERN_CONT in printk() continuation linesKay Sievers2012-05-081-3/+3
| | | | | | | | | | | | Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | mm: raise MemFree by reverting percpu_pagelist_fraction to 0Hugh Dickins2012-05-111-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Why is there less MemFree than there used to be? It perturbed a test, so I've just been bisecting linux-next, and now find the offender went upstream yesterday. Commit 93278814d359 "mm: fix division by 0 in percpu_pagelist_fraction()" mistakenly initialized percpu_pagelist_fraction to the sysctl's minimum 8, which leaves 1/8th of memory on percpu lists (on each cpu??); but most of us expect it to be left unset at 0 (and it's not then used as a divisor). MemTotal: 8061476kB 8061476kB 8061476kB 8061476kB 8061476kB 8061476kB Repetitive test with percpu_pagelist_fraction 8: MemFree: 6948420kB 6237172kB 6949696kB 6840692kB 6949048kB 6862984kB Same test with percpu_pagelist_fraction back to 0: MemFree: 7945000kB 7944908kB 7948568kB 7949060kB 7948796kB 7948812kB Signed-off-by: Hugh Dickins <hughd@google.com> [ We really should fix the crazy sysctl interface too, but that's a separate thing - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: fix division by 0 in percpu_pagelist_fraction()Sasha Levin2012-05-101-2/+2
|/ | | | | | | | | | | | | | percpu_pagelist_fraction_sysctl_handler() has only considered -EINVAL as a possible error from proc_dointvec_minmax(). If any other error is returned, it would proceed to divide by zero since percpu_pagelist_fraction wasn't getting initialized at any point. For example, writing 0 bytes into the proc file would trigger the issue. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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