The patch titled zonelists: handle a node zonelist with no applicable entries has been added to the -mm tree. Its filename is zonelists-handle-a-node-zonelist-with-no-applicable-entries.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: zonelists: handle a node zonelist with no applicable entries From: Andy Whitcroft <apw@xxxxxxxxxxxx> 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@xxxxxxxxxxxx> Acked-by: Mel Gorman <mel@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 3 +++ 1 file changed, 3 insertions(+) diff -puN mm/page_alloc.c~zonelists-handle-a-node-zonelist-with-no-applicable-entries mm/page_alloc.c --- a/mm/page_alloc.c~zonelists-handle-a-node-zonelist-with-no-applicable-entries +++ a/mm/page_alloc.c @@ -1396,6 +1396,9 @@ get_page_from_freelist(gfp_t gfp_mask, n (void)first_zones_zonelist(zonelist, high_zoneidx, nodemask, &preferred_zone); + if (!preferred_zone) + return NULL; + classzone_idx = zone_idx(preferred_zone); zonelist_scan: _ Patches currently in -mm which might be from apw@xxxxxxxxxxxx are linux-next.patch zonelists-handle-a-node-zonelist-with-no-applicable-entries.patch mm-add-a-basic-debugging-framework-for-memory-initialisation.patch mm-add-a-basic-debugging-framework-for-memory-initialisation-fix.patch mm-verify-the-page-links-and-memory-model.patch mm-make-defensive-checks-around-pfn-values-registered-for-memory-usage.patch mm-print-out-the-zonelists-on-request-for-manual-verification.patch mm-move-bootmem-descriptors-definition-to-a-single-place.patch mm-fix-free_all_bootmem_core-alignment-check.patch mm-normalize-internal-argument-passing-of-bootmem-data.patch mm-unexport-__alloc_bootmem_core.patch buddy-clarify-comments-describing-buddy-merge.patch update-checkpatchpl-to-version-019.patch update-checkpatchpl-to-version-019-fix.patch page-owner-tracking-leak-detector.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html