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authorAndy Whitcroft <apw@shadowen.org>2008-05-23 13:04:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-05-24 09:56:11 -0700
commit7eb54824b76793dd86afb54f182ef9aa64b3a45a (patch)
tree400753c14099e9ecbba9ab4665b4c1badd180839 /mm
parent03a74dcc7eebe6edd778317e82fafdf71e68488c (diff)
downloadop-kernel-dev-7eb54824b76793dd86afb54f182ef9aa64b3a45a.zip
op-kernel-dev-7eb54824b76793dd86afb54f182ef9aa64b3a45a.tar.gz
zonelists: handle a node zonelist with no applicable entries
When booting 2.6.26-rc3 on a multi-node x86_32 numa system we are seeing panics when trying node local allocations: BUG: unable to handle kernel NULL pointer dereference at 0000034c IP: [<c1042507>] get_page_from_freelist+0x4a/0x18e *pdpt = 00000000013a7001 *pde = 0000000000000000 Oops: 0000 [#1] SMP Modules linked in: Pid: 0, comm: swapper Not tainted (2.6.26-rc3-00003-g5abc28d #82) EIP: 0060:[<c1042507>] EFLAGS: 00010282 CPU: 0 EIP is at get_page_from_freelist+0x4a/0x18e EAX: c1371ed8 EBX: 00000000 ECX: 00000000 EDX: 00000000 ESI: f7801180 EDI: 00000000 EBP: 00000000 ESP: c1371ec0 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 Process swapper (pid: 0, ti=c1370000 task=c12f5b40 task.ti=c1370000) Stack: 00000000 00000000 00000000 00000000 000612d0 000412d0 00000000 000412d0 f7801180 f7c0101c f7c01018 c10426e4 f7c01018 00000001 00000044 00000000 00000001 c12f5b40 00000001 00000010 00000000 000412d0 00000286 000412d0 Call Trace: [<c10426e4>] __alloc_pages_internal+0x99/0x378 [<c10429ca>] __alloc_pages+0x7/0x9 [<c105e0e8>] kmem_getpages+0x66/0xef [<c105ec55>] cache_grow+0x8f/0x123 [<c105f117>] ____cache_alloc_node+0xb9/0xe4 [<c105f427>] kmem_cache_alloc_node+0x92/0xd2 [<c122118c>] setup_cpu_cache+0xaf/0x177 [<c105e6ca>] kmem_cache_create+0x2c8/0x353 [<c13853af>] kmem_cache_init+0x1ce/0x3ad [<c13755c5>] start_kernel+0x178/0x1ee This occurs when we are scanning the zonelists looking for a ZONE_NORMAL page. In this system there is only ZONE_DMA and ZONE_NORMAL memory on node 0, all other nodes are mapped above 4GB physical. Here is a dump of the zonelists from this system: zonelists pgdat=c1400000 0: c14006c0:2 f7c006c0:2 f7e006c0:2 c1400360:1 c1400000:0 1: c14006c0:2 c1400360:1 c1400000:0 zonelists pgdat=f7c00000 0: f7c006c0:2 f7e006c0:2 c14006c0:2 c1400360:1 c1400000:0 1: f7c006c0:2 zonelists pgdat=f7e00000 0: f7e006c0:2 c14006c0:2 f7c006c0:2 c1400360:1 c1400000:0 1: f7e006c0:2 When performing a node local allocation we call get_page_from_freelist() looking for a page. It in turn calls first_zones_zonelist() which returns a preferred_zone. Where there are no applicable zones this will be NULL. However we use this unconditionally, leading to this panic. Where there are no applicable zones there is no possibility of a successful allocation, so simply fail the allocation. Signed-off-by: Andy Whitcroft <apw@shadowen.org> 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>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0353002..7f4c66f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1396,6 +1396,9 @@ get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,
(void)first_zones_zonelist(zonelist, high_zoneidx, nodemask,
&preferred_zone);
+ if (!preferred_zone)
+ return NULL;
+
classzone_idx = zone_idx(preferred_zone);
zonelist_scan:
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