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* hugetlb: follow_hugetlb_page() for write accessAdam Litke2007-11-141-1/+1
| | | | | | | | | | | | | | | | | | | | | | When calling get_user_pages(), a write flag is passed in by the caller to indicate if write access is required on the faulted-in pages. Currently, follow_hugetlb_page() ignores this flag and always faults pages for read-only access. This can cause data corruption because a device driver that calls get_user_pages() with write set will not expect COW faults to occur on the returned pages. This patch passes the write flag down to follow_hugetlb_page() and makes sure hugetlb_fault() is called with the right write_access parameter. [ezk@cs.sunysb.edu: build fix] Signed-off-by: Adam Litke <agl@us.ibm.com> Reviewed-by: Ken Chen <kenchen@google.com> Cc: David Gibson <hermes@gibson.dropbear.id.au> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* unexport access_process_vmAdrian Bunk2007-11-051-1/+0
| | | | | | | This patch removes the no longer used EXPORT_SYMBOL_GPL(access_process_vm). Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* spelling fixes: mm/Simon Arlott2007-10-201-1/+1
| | | | | | | Spelling fixes in mm/. Signed-off-by: Simon Arlott <simon@fire.lp0.eu> Signed-off-by: Adrian Bunk <bunk@kernel.org>
* remove unused flush_tlb_pgtablesBenjamin Herrenschmidt2007-10-191-3/+0
| | | | | | | | | | Nobody uses flush_tlb_pgtables anymore, this patch removes all remaining traces of it from all archs. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* flush icache before set_pte() on ia64: flush icache at set_pteKAMEZAWA Hiroyuki2007-10-161-7/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Current ia64 kernel flushes icache by lazy_mmu_prot_update() *after* set_pte(). This is too late. This patch removes lazy_mmu_prot_update and add modfied set_pte() for flushing if necessary. This patch flush icache of a page when new pte has exec bit. && new pte has present bit && new pte is user's page. && (old *ptep is not present || new pte's pfn is not same to old *ptep's ptn) && new pte's page has no Pg_arch_1 bit. Pg_arch_1 is set when a page is cache consistent. I think this condition checks are much easier to understand than considering "Where sync_icache_dcache() should be inserted ?". pte_user() for ia64 was removed by http://lkml.org/lkml/2007/6/12/67 as clean-up. So, I added it again. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* calculation of pgoff in do_linear_fault() uses mixed unitsDean Nelson2007-10-161-1/+1
| | | | | | | | | | | | | The calculation of pgoff in do_linear_fault() should use PAGE_SHIFT and not PAGE_CACHE_SHIFT since vma->vm_pgoff is in units of PAGE_SIZE and not PAGE_CACHE_SIZE. At the moment linux/pagemap.h has PAGE_CACHE_SHIFT defined as PAGE_SHIFT, but should that ever change this calculation would break. Signed-off-by: Dean Nelson <dcn@sgi.com> Acked-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* remove ZERO_PAGENick Piggin2007-10-161-130/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The commit b5810039a54e5babf428e9a1e89fc1940fabff11 contains the note A last caveat: the ZERO_PAGE is now refcounted and managed with rmap (and thus mapcounted and count towards shared rss). These writes to the struct page could cause excessive cacheline bouncing on big systems. There are a number of ways this could be addressed if it is an issue. And indeed this cacheline bouncing has shown up on large SGI systems. There was a situation where an Altix system was essentially livelocked tearing down ZERO_PAGE pagetables when an HPC app aborted during startup. This situation can be avoided in userspace, but it does highlight the potential scalability problem with refcounting ZERO_PAGE, and corner cases where it can really hurt (we don't want the system to livelock!). There are several broad ways to fix this problem: 1. add back some special casing to avoid refcounting ZERO_PAGE 2. per-node or per-cpu ZERO_PAGES 3. remove the ZERO_PAGE completely I will argue for 3. The others should also fix the problem, but they result in more complex code than does 3, with little or no real benefit that I can see. Why? Inserting a ZERO_PAGE for anonymous read faults appears to be a false optimisation: if an application is performance critical, it would not be doing many read faults of new memory, or at least it could be expected to write to that memory soon afterwards. If cache or memory use is critical, it should not be working with a significant number of ZERO_PAGEs anyway (a more compact representation of zeroes should be used). As a sanity check -- mesuring on my desktop system, there are never many mappings to the ZERO_PAGE (eg. 2 or 3), thus memory usage here should not increase much without it. When running a make -j4 kernel compile on my dual core system, there are about 1,000 mappings to the ZERO_PAGE created per second, but about 1,000 ZERO_PAGE COW faults per second (less than 1 ZERO_PAGE mapping per second is torn down without being COWed). So removing ZERO_PAGE will save 1,000 page faults per second when running kbuild, while keeping it only saves less than 1 page clearing operation per second. 1 page clear is cheaper than a thousand faults, presumably, so there isn't an obvious loss. Neither the logical argument nor these basic tests give a guarantee of no regressions. However, this is a reasonable opportunity to try to remove the ZERO_PAGE from the pagefault path. If it is found to cause regressions, we can reintroduce it and just avoid refcounting it. The /dev/zero ZERO_PAGE usage and TLB tricks also get nuked. I don't see much use to them except on benchmarks. All other users of ZERO_PAGE are converted just to use ZERO_PAGE(0) for simplicity. We can look at replacing them all and maybe ripping out ZERO_PAGE completely when we are more satisfied with this solution. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus "snif" Torvalds <torvalds@linux-foundation.org>
* mm: set_page_dirty_balance() vs ->page_mkwrite()Peter Zijlstra2007-10-081-2/+7
| | | | | | | | | | | | | | All the current page_mkwrite() implementations also set the page dirty. Which results in the set_page_dirty_balance() call to _not_ call balance, because the page is already found dirty. This allows us to dirty a _lot_ of pages without ever hitting balance_dirty_pages(). Not good (tm). Force a balance call if ->page_mkwrite() was successful. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Fix sys_remap_file_pages BUG at highmem.c:15!Hugh Dickins2007-10-041-8/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Gurudas Pai reports kernel BUG at arch/i386/mm/highmem.c:15! below sys_remap_file_pages, while running Oracle database test on x86 in 6GB RAM: kunmap thinks we're in_interrupt because the preempt count has wrapped. That's because __do_fault expected to unmap page_table, but one of its two callers do_nonlinear_fault already unmapped it: let do_linear_fault unmap it first too, and then there's no need to pass the page_table arg down. Why have we been so slow to notice this? Probably through forgetting that the mapping_cap_account_dirty test means that sys_remap_file_pages nowadays only goes the full nonlinear vma route on a few memory-backed filesystems like ramfs, tmpfs and hugetlbfs. [ It also depends on CONFIG_HIGHPTE, so it becomes even harder to trigger in practice. Many who have need of large memory have probably migrated to x86-64.. Problem introduced by commit d0217ac04ca6591841e5665f518e38064f4e65bd ("mm: fault feedback #1") -- Linus ] Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: gurudas pai <gurudas.pai@oracle.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* remove handle_mm_fault exportChristoph Hellwig2007-07-211-2/+0
| | | | | | | | | | Now that arch/powerpc/platforms/cell/spufs/fault.c is always built in the kernel there is no need to export handle_mm_fault anymore. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lguest: export symbols for lguest as a moduleRusty Russell2007-07-191-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | lguest does some fairly lowlevel things to support a host, which normal modules don't need: math_state_restore: When the guest triggers a Device Not Available fault, we need to be able to restore the FPU __put_task_struct: We need to hold a reference to another task for inter-guest I/O, and put_task_struct() is an inline function which calls __put_task_struct. access_process_vm: We need to access another task for inter-guest I/O. map_vm_area & __get_vm_area: We need to map the switcher shim (ie. monitor) at 0xFFC01000. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix clear_page_dirty_for_io vs fault raceNick Piggin2007-07-191-0/+9
| | | | | | | | | | | | | | Fix msync data loss and (less importantly) dirty page accounting inaccuracies due to the race remaining in clear_page_dirty_for_io(). The deleted comment explains what the race was, and the added comments explain how it is fixed. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fault feedback #2Nick Piggin2007-07-191-40/+40
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch completes Linus's wish that the fault return codes be made into bit flags, which I agree makes everything nicer. This requires requires all handle_mm_fault callers to be modified (possibly the modifications should go further and do things like fault accounting in handle_mm_fault -- however that would be for another patch). [akpm@linux-foundation.org: fix alpha build] [akpm@linux-foundation.org: fix s390 build] [akpm@linux-foundation.org: fix sparc build] [akpm@linux-foundation.org: fix sparc64 build] [akpm@linux-foundation.org: fix ia64 build] Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ian Molton <spyro@f2s.com> Cc: Bryan Wu <bryan.wu@analog.com> Cc: Mikael Starvik <starvik@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Greg Ungerer <gerg@uclinux.org> Cc: Matthew Wilcox <willy@debian.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp> Cc: Richard Curnow <rc@rc0.org.uk> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp> Cc: Chris Zankel <chris@zankel.net> Acked-by: Kyle McMartin <kyle@mcmartin.ca> Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> [ Still apparently needs some ARM and PPC loving - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fault feedback #1Nick Piggin2007-07-191-57/+52
| | | | | | | | | | | | | | | | | | | | | | | | Change ->fault prototype. We now return an int, which contains VM_FAULT_xxx code in the low byte, and FAULT_RET_xxx code in the next byte. FAULT_RET_ code tells the VM whether a page was found, whether it has been locked, and potentially other things. This is not quite the way he wanted it yet, but that's changed in the next patch (which requires changes to arch code). This means we no longer set VM_CAN_INVALIDATE in the vma in order to say that a page is locked which requires filemap_nopage to go away (because we can no longer remain backward compatible without that flag), but we were going to do that anyway. struct fault_data is renamed to struct vm_fault as Linus asked. address is now a void __user * that we should firmly encourage drivers not to use without really good reason. The page is now returned via a page pointer in the vm_fault struct. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ocfs2: release page lock before calling ->page_mkwriteMark Fasheh2007-07-191-5/+9
| | | | | | | | | | | | __do_fault() was calling ->page_mkwrite() with the page lock held, which violates the locking rules for that callback. Release and retake the page lock around the callback to avoid deadlocking file systems which manually take it. Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: merge populate and nopage into fault (fixes nonlinear)Nick Piggin2007-07-191-46/+86
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Nonlinear mappings are (AFAIKS) simply a virtual memory concept that encodes the virtual address -> file offset differently from linear mappings. ->populate is a layering violation because the filesystem/pagecache code should need to know anything about the virtual memory mapping. The hitch here is that the ->nopage handler didn't pass down enough information (ie. pgoff). But it is more logical to pass pgoff rather than have the ->nopage function calculate it itself anyway (because that's a similar layering violation). Having the populate handler install the pte itself is likewise a nasty thing to be doing. This patch introduces a new fault handler that replaces ->nopage and ->populate and (later) ->nopfn. Most of the old mechanism is still in place so there is a lot of duplication and nice cleanups that can be removed if everyone switches over. The rationale for doing this in the first place is that nonlinear mappings are subject to the pagefault vs invalidate/truncate race too, and it seemed stupid to duplicate the synchronisation logic rather than just consolidate the two. After this patch, MAP_NONBLOCK no longer sets up ptes for pages present in pagecache. Seems like a fringe functionality anyway. NOPAGE_REFAULT is removed. This should be implemented with ->fault, and no users have hit mainline yet. [akpm@linux-foundation.org: cleanup] [randy.dunlap@oracle.com: doc. fixes for readahead] [akpm@linux-foundation.org: build fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix fault vs invalidate race for linear mappingsNick Piggin2007-07-191-80/+73
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix the race between invalidate_inode_pages and do_no_page. Andrea Arcangeli identified a subtle race between invalidation of pages from pagecache with userspace mappings, and do_no_page. The issue is that invalidation has to shoot down all mappings to the page, before it can be discarded from the pagecache. Between shooting down ptes to a particular page, and actually dropping the struct page from the pagecache, do_no_page from any process might fault on that page and establish a new mapping to the page just before it gets discarded from the pagecache. The most common case where such invalidation is used is in file truncation. This case was catered for by doing a sort of open-coded seqlock between the file's i_size, and its truncate_count. Truncation will decrease i_size, then increment truncate_count before unmapping userspace pages; do_no_page will read truncate_count, then find the page if it is within i_size, and then check truncate_count under the page table lock and back out and retry if it had subsequently been changed (ptl will serialise against unmapping, and ensure a potentially updated truncate_count is actually visible). Complexity and documentation issues aside, the locking protocol fails in the case where we would like to invalidate pagecache inside i_size. do_no_page can come in anytime and filemap_nopage is not aware of the invalidation in progress (as it is when it is outside i_size). The end result is that dangling (->mapping == NULL) pages that appear to be from a particular file may be mapped into userspace with nonsense data. Valid mappings to the same place will see a different page. Andrea implemented two working fixes, one using a real seqlock, another using a page->flags bit. He also proposed using the page lock in do_no_page, but that was initially considered too heavyweight. However, it is not a global or per-file lock, and the page cacheline is modified in do_no_page to increment _count and _mapcount anyway, so a further modification should not be a large performance hit. Scalability is not an issue. This patch implements this latter approach. ->nopage implementations return with the page locked if it is possible for their underlying file to be invalidated (in that case, they must set a special vm_flags bit to indicate so). do_no_page only unlocks the page after setting up the mapping completely. invalidation is excluded because it holds the page lock during invalidation of each page (and ensures that the page is not mapped while holding the lock). This also allows significant simplifications in do_no_page, because we have the page locked in the right place in the pagecache from the start. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Add __GFP_MOVABLE for callers to flag allocations from high memory that may ↵Mel Gorman2007-07-171-4/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | be migrated It is often known at allocation time whether a page may be migrated or not. This patch adds a flag called __GFP_MOVABLE and a new mask called GFP_HIGH_MOVABLE. Allocations using the __GFP_MOVABLE can be either migrated using the page migration mechanism or reclaimed by syncing with backing storage and discarding. An API function very similar to alloc_zeroed_user_highpage() is added for __GFP_MOVABLE allocations called alloc_zeroed_user_highpage_movable(). The flags used by alloc_zeroed_user_highpage() are not changed because it would change the semantics of an existing API. After this patch is applied there are no in-kernel users of alloc_zeroed_user_highpage() so it probably should be marked deprecated if this patch is merged. Note that this patch includes a minor cleanup to the use of __GFP_ZERO in shmem.c to keep all flag modifications to inode->mapping in the shmem_dir_alloc() helper function. This clean-up suggestion is courtesy of Hugh Dickens. Additional credit goes to Christoph Lameter and Linus Torvalds for shaping the concept. Credit to Hugh Dickens for catching issues with shmem swap vector and ramfs allocations. [akpm@linux-foundation.org: build fix] [hugh@veritas.com: __GFP_ZERO cleanup] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kill vmalloc_earlyreserveJan Beulich2007-07-161-2/+0
| | | | | | | | This symbol got orphaned quite a while ago. Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* oom: stop allocating user memory if TIF_MEMDIE is setEthan Solomita2007-07-161-0/+8
| | | | | | | | | | | | | get_user_pages() can try to allocate a nearly unlimited amount of memory on behalf of a user process, even if that process has been OOM killed. The OOM kill occurs upon return to user space via a SIGKILL, but get_user_pages() will try allocate all its memory before returning. Change get_user_pages() to check for TIF_MEMDIE, and if set then return immediately. Signed-off-by: Ethan Solomita <solo@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* MM: use DIV_ROUND_UP() in mm/memory.cRolf Eike Beer2007-07-161-1/+1
| | | | | | | | Replace a hand coded version of DIV_ROUND_UP(). Signed-off-by: Rolf Eike Beer <eike-kernel@sf-tec.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Rework ptep_set_access_flags and fix sun4cBenjamin Herrenschmidt2007-06-161-7/+6
| | | | | | | | | | | | | | | | | | | | | Some changes done a while ago to avoid pounding on ptep_set_access_flags and update_mmu_cache in some race situations break sun4c which requires update_mmu_cache() to always be called on minor faults. This patch reworks ptep_set_access_flags() semantics, implementations and callers so that it's now responsible for returning whether an update is necessary or not (basically whether the PTE actually changed). This allow fixing the sparc implementation to always return 1 on sun4c. [akpm@linux-foundation.org: fixes, cleanups] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: David Miller <davem@davemloft.net> Cc: Mark Fortescue <mark@mtfhpc.demon.co.uk> Acked-by: William Lee Irwin III <wli@holomorphy.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: more rmap checkingNick Piggin2007-05-171-1/+1
| | | | | | | | | | | | | | Re-introduce rmap verification patches that Hugh removed when he removed PG_map_lock. PG_map_lock actually isn't needed to synchronise access to anonymous pages, because PG_locked and PTL together already do. These checks were important in discovering and fixing a rare rmap corruption in SLES9. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Add unitialized_var() macro for suppressing gcc warningsBorislav Petkov2007-05-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | Introduce a macro for suppressing gcc from generating a warning about a probable uninitialized state of a variable. Example: - spinlock_t *ptl; + spinlock_t *uninitialized_var(ptl); Not a happy solution, but those warnings are obnoxious. - Using the usual pointlessly-set-it-to-zero approach wastes several bytes of text. - Using a macro means we can (hopefully) do something else if gcc changes cause the `x = x' hack to stop working - Using a macro means that people who are worried about hiding true bugs can easily turn it off. Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove gcc workaroundNick Piggin2007-05-071-12/+0
| | | | | | | | | | | | Minimum gcc version is 3.2 now. However, with likely profiling, even modern gcc versions cannot always eliminate the call. Replace the placeholder functions with the more conventional empty static inlines, which should be optimal for everyone. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Add apply_to_page_range() which applies a function to a pte rangeJeremy Fitzhardinge2007-05-071-0/+94
| | | | | | | | | | | | | | | | | | | | | | | | Add a new mm function apply_to_page_range() which applies a given function to every pte in a given virtual address range in a given mm structure. This is a generic alternative to cut-and-pasting the Linux idiomatic pagetable walking code in every place that a sequence of PTEs must be accessed. Although this interface is intended to be useful in a wide range of situations, it is currently used specifically by several Xen subsystems, for example: to ensure that pagetables have been allocated for a virtual address range, and to construct batched special pagetable update requests to map I/O memory (in ioremap()). [akpm@linux-foundation.org: fix warning, unpleasantly] Signed-off-by: Ian Pratt <ian.pratt@xensource.com> Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Matt Mackall <mpm@waste.org> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] Add NOPFN_REFAULT result from vm_ops->nopfn()Benjamin Herrenschmidt2007-02-121-2/+4
| | | | | | | | | | | | | Add a NOPFN_REFAULT return code for vm_ops->nopfn() equivalent to NOPAGE_REFAULT for vmops->nopage() indicating that the handler requests a re-execution of the faulting instruction Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Arnd Bergmann <arnd.bergmann@de.ibm.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] add vm_insert_pfn()Nick Piggin2007-02-121-0/+45
| | | | | | | | | | | | | Add a vm_insert_pfn helper, so that ->fault handlers can have nopfn functionality by installing their own pte and returning NULL. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Arnd Bergmann <arnd.bergmann@de.ibm.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] Numerous fixes to kernel-doc info in source files.Robert P. J. Day2007-02-111-3/+1
| | | | | | | | | | | | | | | A variety of (mostly) innocuous fixes to the embedded kernel-doc content in source files, including: * make multi-line initial descriptions single line * denote some function names, constants and structs as such * change erroneous opening '/*' to '/**' in a few places * reword some text for clarity Signed-off-by: Robert P. J. Day <rpjday@mindspring.com> Cc: "Randy.Dunlap" <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] do not disturb page referenced state when unmapping memory rangeKen Chen2007-02-111-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When kernel unmaps an address range, it needs to transfer PTE state into page struct. Currently, kernel transfer access bit via mark_page_accessed(). The call to mark_page_accessed in the unmap path doesn't look logically correct. At unmap time, calling mark_page_accessed will causes page LRU state to be bumped up one step closer to more recently used state. It is causing quite a bit headache in a scenario when a process creates a shmem segment, touch a whole bunch of pages, then unmaps it. The unmapping takes a long time because mark_page_accessed() will start moving pages from inactive to active list. I'm not too much concerned with moving the page from one list to another in LRU. Sooner or later it might be moved because of multiple mappings from various processes. But it just doesn't look logical that when user asks a range to be unmapped, it's his intention that the process is no longer interested in these pages. Moving those pages to active list (or bumping up a state towards more active) seems to be an over reaction. It also prolongs unmapping latency which is the core issue I'm trying to solve. As suggested by Peter, we should still preserve the info on pte young pages, but not more. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ken Chen <kenchen@google.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] page_mkwrite caller race fixHugh Dickins2007-02-111-2/+1
| | | | | | | | | | | | After do_wp_page has tested page_mkwrite, it must release old_page after acquiring page table lock, not before: at some stage that ordering got reversed, leaving a (very unlikely) window in which old_page might be truncated, freed, and reused in the same position. Signed-off-by: Hugh Dickins <hugh@veritas.com> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] i386 vDSO: use VM_ALWAYSDUMPRoland McGrath2007-01-261-0/+7
| | | | | | | | | | | | | | | | | | | | | | | This patch fixes core dumps to include the vDSO vma, which is left out now. It removes the special-case core writing macros, which were not doing the right thing for the vDSO vma anyway. Instead, it uses VM_ALWAYSDUMP in the vma; there is no need for the fixmap page to be installed. It handles the CONFIG_COMPAT_VDSO case by making elf_core_dump use the fake vma from get_gate_vma after real vmas in the same way the /proc/PID/maps code does. This changes core dumps so they no longer include the non-PT_LOAD phdrs from the vDSO. I made the change to add them in the first place, but in turned out that nothing ever wanted them there since the advent of NT_AUXV. It's cleaner to leave them out, and just let the phdrs inside the vDSO image speak for themselves. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] Fix gate_vma.vm_flagsRoland McGrath2007-01-261-2/+2
| | | | | | | | | | | | | | | This patch fixes the initialization of gate_vma.vm_flags and gate_vma.vm_page_prot to reflect reality. This makes the "[vdso]" line in /proc/PID/maps correctly show r-xp instead of ---p, when gate_vma is used (CONFIG_COMPAT_VDSO on i386). Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [ARM] pass vma for flush_anon_page()Russell King2007-01-081-1/+1
| | | | | | | | | | | | | | | Since get_user_pages() may be used with processes other than the current process and calls flush_anon_page(), flush_anon_page() has to cope in some way with non-current processes. It may not be appropriate, or even desirable to flush a region of virtual memory cache in the current process when that is different to the process that we want the flush to occur for. Therefore, pass the vma into flush_anon_page() so that the architecture can work out whether the 'vmaddr' is for the current process or not. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* [PATCH] mm: more rmap debuggingNick Piggin2006-12-221-2/+2
| | | | | | | | | Add more debugging in the rmap code in an attempt to locate to source of the occasional "mapcount went negative" assertions. Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Pass vma argument to copy_user_highpage().Atsushi Nemoto2006-12-131-5/+5
| | | | | | | | | | | | | To allow a more effective copy_user_highpage() on certain architectures, a vma argument is added to the function and cow_user_page() allowing the implementation of these functions to check for the VM_EXEC bit. The main part of this patch was originally written by Ralf Baechle; Atushi Nemoto did the the debugging. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] read_zero_pagealigned() locking fixHugh Dickins2006-12-101-11/+21
| | | | | | | | | | | | | | | | | | | | | | | | | Ramiro Voicu hits the BUG_ON(!pte_none(*pte)) in zeromap_pte_range: kernel bugzilla 7645. Right: read_zero_pagealigned uses down_read of mmap_sem, but another thread's racing read of /dev/zero, or a normal fault, can easily set that pte again, in between zap_page_range and zeromap_page_range getting there. It's been wrong ever since 2.4.3. The simple fix is to use down_write instead, but that would serialize reads of /dev/zero more than at present: perhaps some app would be badly affected. So instead let zeromap_page_range return the error instead of BUG_ON, and read_zero_pagealigned break to the slower clear_user loop in that case - there's no need to optimize for it. Use -EEXIST for when a pte is found: BUG_ON in mmap_zero (the other user of zeromap_page_range), though it really isn't interesting there. And since mmap_zero wants -EAGAIN for out-of-memory, the zeromaps better return that than -ENOMEM. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Ramiro Voicu: <Ramiro.Voicu@cern.ch> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] remove EXPORT_UNUSED_SYMBOL'ed symbolsAdrian Bunk2006-12-071-1/+0
| | | | | | | | In time for 2.6.20, we can get rid of this junk. Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] grab swap token reorderedAshwin Chaugule2006-12-071-1/+1
| | | | | | | | | | | Make sure the contention for the token happens _before_ any read-in and kicks the swap-token algo only when the VM is under pressure. Signed-off-by: Ashwin Chaugule <ashwin.chaugule@celunite.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: D-cache aliasing issue in cow_user_pageDmitriy Monakhov2006-10-201-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | --=-=-= from mm/memory.c: 1434 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va) 1435 { 1436 /* 1437 * If the source page was a PFN mapping, we don't have 1438 * a "struct page" for it. We do a best-effort copy by 1439 * just copying from the original user address. If that 1440 * fails, we just zero-fill it. Live with it. 1441 */ 1442 if (unlikely(!src)) { 1443 void *kaddr = kmap_atomic(dst, KM_USER0); 1444 void __user *uaddr = (void __user *)(va & PAGE_MASK); 1445 1446 /* 1447 * This really shouldn't fail, because the page is there 1448 * in the page tables. But it might just be unreadable, 1449 * in which case we just give up and fill the result with 1450 * zeroes. 1451 */ 1452 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 1453 memset(kaddr, 0, PAGE_SIZE); 1454 kunmap_atomic(kaddr, KM_USER0); #### D-cache have to be flushed here. #### It seems it is just forgotten. 1455 return; 1456 1457 } 1458 copy_user_highpage(dst, src, va); #### Ok here. flush_dcache_page() called from this func if arch need it 1459 } Following is the patch fix this issue: Signed-off-by: Dmitriy Monakhov <dmonakhov@openvz.org> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] page fault retry with NOPAGE_REFAULTBenjamin Herrenschmidt2006-10-061-3/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a way for a no_page() handler to request a retry of the faulting instruction. It goes back to userland on page faults and just tries again in get_user_pages(). I added a cond_resched() in the loop in that later case. The problem I have with signal and spufs is an actual bug affecting apps and I don't see other ways of fixing it. In addition, we are having issues with infiniband and 64k pages (related to the way the hypervisor deals with some HV cards) that will require us to muck around with the MMU from within the IB driver's no_page() (it's a pSeries specific driver) and return to the caller the same way using NOPAGE_REFAULT. And to add to this, the graphics folks have been following a new approach of memory management that involves transparently swapping objects between video ram and main meory. To do that, they need installing PTEs from a no_page() handler as well and that also requires returning with NOPAGE_REFAULT. (For the later, they are currently using io_remap_pfn_range to install one PTE from no_page() which is a bit racy, we need to add a check for the PTE having already been installed afer taking the lock, but that's ok, they are only at the proof-of-concept stage. I'll send a patch adding a "clean" function to do that, we can use that from spufs too and get rid of the sparsemem hacks we do to create struct page for SPEs. Basically, that provides a generic solution for being able to have no_page() map hardware devices, which is something that I think sound driver folks have been asking for some time too). All of these things depend on having the NOPAGE_REFAULT exit path from no_page() handlers. Signed-off-by: Benjamin Herrenchmidt <benh@kernel.crashing.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] paravirt: lazy mmu mode hooks.patchZachary Amsden2006-10-011-0/+8
| | | | | | | | | | | | | | | | | | | | | | | Implement lazy MMU update hooks which are SMP safe for both direct and shadow page tables. The idea is that PTE updates and page invalidations while in lazy mode can be batched into a single hypercall. We use this in VMI for shadow page table synchronization, and it is a win. It also can be used by PPC and for direct page tables on Xen. For SMP, the enter / leave must happen under protection of the page table locks for page tables which are being modified. This is because otherwise, you end up with stale state in the batched hypercall, which other CPUs can race ahead of. Doing this under the protection of the locks guarantees the synchronization is correct, and also means that spurious faults which are generated during this window by remote CPUs are properly handled, as the page fault handler must re-check the PTE under protection of the same lock. Signed-off-by: Zachary Amsden <zach@vmware.com> Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] paravirt: pte clear not presentZachary Amsden2006-10-011-1/+1
| | | | | | | | | | | | | | Change pte_clear_full to a more appropriately named pte_clear_not_present, allowing optimizations when not-present mapping changes need not be reflected in the hardware TLB for protected page table modes. There is also another case that can use it in the fremap code. Signed-off-by: Zachary Amsden <zach@vmware.com> Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] paravirt: remove read hazard from cowZachary Amsden2006-10-011-1/+1
| | | | | | | | | | | | | We don't want to read PTEs directly like this after they have been modified, as a lazy MMU implementation of direct page tables may not have written the updated PTE back to memory yet. Signed-off-by: Zachary Amsden <zach@vmware.com> Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: fix a race condition under SMC + COWSiddha, Suresh B2006-09-291-1/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Failing context is a multi threaded process context and the failing sequence is as follows. One thread T0 doing self modifying code on page X on processor P0 and another thread T1 doing COW (breaking the COW setup as part of just happened fork() in another thread T2) on the same page X on processor P1. T0 doing SMC can endup modifying the new page Y (allocated by the T1 doing COW on P1) but because of different I/D TLB's, P0 ITLB will not see the new mapping till the flush TLB IPI from P1 is received. During this interval, if T0 executes the code created by SMC it can result in an app error (as ITLB still points to old page X and endup executing the content in page X rather than using the content in page Y). Fix this issue by first clearing the PTE and flushing it, before updating it with new entry. Hugh sayeth: I was a bit sceptical, in the habit of thinking that Self Modifying Code must look such issues itself: but I guess there's nothing it can do to avoid this one. Fair enough, what you're changing it to is pretty much what powerpc and s390 were already doing, and is a more robust way of proceeding, consistent with how ptes are set everywhere else. The ptep_clear_flush is a bit heavy-handed (it's anxious to return the pte that was atomically cleared), but we'd have to wander through lots of arches to get the right minimal behaviour. It'd also be nice to eliminate ptep_establish completely, now only used to define other macros/inlines: it always seemed obfuscation to me, what you've got there now is clearer. Let's put those cleanups on a TODO list. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] NOMMU: Check that access_process_vm() has a valid targetDavid Howells2006-09-271-0/+53
| | | | | | | | | | | | Check that access_process_vm() is accessing a valid mapping in the target process. This limits ptrace() accesses and accesses through /proc/<pid>/maps to only those regions actually mapped by a program. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] do_no_pfn()Jes Sorensen2006-09-271-5/+59
| | | | | | | | | | | | | | | | | | | | | | | Implement do_no_pfn() for handling mapping of memory without a struct page backing it. This avoids creating fake page table entries for regions which are not backed by real memory. This feature is used by the MSPEC driver and other users, where it is highly undesirable to have a struct page sitting behind the page (for instance if the page is accessed in cached mode via the struct page in parallel to the the driver accessing it uncached, which can result in data corruption on some architectures, such as ia64). This version uses specific NOPFN_{SIGBUS,OOM} return values, rather than expect all negative pfn values would be an error. It also bugs on cow mappings as this would not work with the VM. [akpm@osdl.org: micro-optimise] Signed-off-by: Jes Sorensen <jes@sgi.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Add kerneldocs for some functions in mm/memory.cRolf Eike Beer2006-09-261-7/+27
| | | | | | | | | | | These functions are already documented quite well with long comments. Now add kerneldoc style header to make this turn up in everyones favorite doc format. Signed-off-by: Rolf Eike Beer <eike-kernel@sf-tec.de> Cc: "Randy.Dunlap" <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: fixup do_wp_page()Peter Zijlstra2006-09-261-6/+13
| | | | | | | | | | | | | | | | Wrt. the recent modifications in do_wp_page() Hugh Dickins pointed out: "I now realize it's right to the first order (normal case) and to the second order (ptrace poke), but not to the third order (ptrace poke anon page here to be COWed - perhaps can't occur without intervening mprotects)." This patch restores the old COW behaviour for anonymous pages. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: balance dirty pagesPeter Zijlstra2006-09-261-2/+3
| | | | | | | | | | Now that we can detect writers of shared mappings, throttle them. Avoids OOM by surprise. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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