Revision eecc1e426d681351a6026a7d3e7d225f38955b6c authored by Hugh Dickins on 12 January 2014, 09:25:21 UTC, committed by Linus Torvalds on 12 January 2014, 09:47:15 UTC
We see General Protection Fault on RSI in copy_page_rep: that RSI is
what you get from a NULL struct page pointer.
RIP: 0010:[<ffffffff81154955>] [<ffffffff81154955>] copy_page_rep+0x5/0x10
RSP: 0000:ffff880136e15c00 EFLAGS: 00010286
RAX: ffff880000000000 RBX: ffff880136e14000 RCX: 0000000000000200
RDX: 6db6db6db6db6db7 RSI: db73880000000000 RDI: ffff880dd0c00000
RBP: ffff880136e15c18 R08: 0000000000000200 R09: 000000000005987c
R10: 000000000005987c R11: 0000000000000200 R12: 0000000000000001
R13: ffffea00305aa000 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f195752f700(0000) GS:ffff880c7fc20000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000093010000 CR3: 00000001458e1000 CR4: 00000000000027e0
Call Trace:
copy_user_huge_page+0x93/0xab
do_huge_pmd_wp_page+0x710/0x815
handle_mm_fault+0x15d8/0x1d70
__do_page_fault+0x14d/0x840
do_page_fault+0x2f/0x90
page_fault+0x22/0x30
do_huge_pmd_wp_page() tests is_huge_zero_pmd(orig_pmd) four times: but
since shrink_huge_zero_page() can free the huge_zero_page, and we have
no hold of our own on it here (except where the fourth test holds
page_table_lock and has checked pmd_same), it's possible for it to
answer yes the first time, but no to the second or third test. Change
all those last three to tests for NULL page.
(Note: this is not the same issue as trinity's DEBUG_PAGEALLOC BUG
in copy_page_rep with RSI: ffff88009c422000, reported by Sasha Levin
in https://lkml.org/lkml/2013/3/29/103. I believe that one is due
to the source page being split, and a tail page freed, while copy
is in progress; and not a problem without DEBUG_PAGEALLOC, since
the pmd_same check will prevent a miscopy from being made visible.)
Fixes: 97ae17497e99 ("thp: implement refcounting for huge zero page")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@vger.kernel.org # v3.10 v3.11 v3.12
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 518d00b
| File | Mode | Size |
|---|---|---|
| Kconfig | -rw-r--r-- | 19.0 KB |
| Kconfig.debug | -rw-r--r-- | 1015 bytes |
| Makefile | -rw-r--r-- | 2.0 KB |
| backing-dev.c | -rw-r--r-- | 16.5 KB |
| balloon_compaction.c | -rw-r--r-- | 9.6 KB |
| bootmem.c | -rw-r--r-- | 20.8 KB |
| bounce.c | -rw-r--r-- | 6.4 KB |
| cleancache.c | -rw-r--r-- | 12.7 KB |
| compaction.c | -rw-r--r-- | 32.5 KB |
| debug-pagealloc.c | -rw-r--r-- | 2.1 KB |
| dmapool.c | -rw-r--r-- | 13.1 KB |
| fadvise.c | -rw-r--r-- | 3.6 KB |
| failslab.c | -rw-r--r-- | 1.3 KB |
| filemap.c | -rw-r--r-- | 67.7 KB |
| filemap_xip.c | -rw-r--r-- | 11.3 KB |
| fremap.c | -rw-r--r-- | 6.8 KB |
| frontswap.c | -rw-r--r-- | 13.5 KB |
| highmem.c | -rw-r--r-- | 9.9 KB |
| huge_memory.c | -rw-r--r-- | 77.4 KB |
| hugetlb.c | -rw-r--r-- | 92.1 KB |
| hugetlb_cgroup.c | -rw-r--r-- | 10.4 KB |
| hwpoison-inject.c | -rw-r--r-- | 3.3 KB |
| init-mm.c | -rw-r--r-- | 619 bytes |
| internal.h | -rw-r--r-- | 11.2 KB |
| interval_tree.c | -rw-r--r-- | 3.2 KB |
| kmemcheck.c | -rw-r--r-- | 2.8 KB |
| kmemleak-test.c | -rw-r--r-- | 3.3 KB |
| kmemleak.c | -rw-r--r-- | 52.5 KB |
| ksm.c | -rw-r--r-- | 65.8 KB |
| list_lru.c | -rw-r--r-- | 3.1 KB |
| maccess.c | -rw-r--r-- | 1.6 KB |
| madvise.c | -rw-r--r-- | 14.2 KB |
| memblock.c | -rw-r--r-- | 33.1 KB |
| memcontrol.c | -rw-r--r-- | 187.6 KB |
| memory-failure.c | -rw-r--r-- | 46.2 KB |
| memory.c | -rw-r--r-- | 115.7 KB |
| memory_hotplug.c | -rw-r--r-- | 48.4 KB |
| mempolicy.c | -rw-r--r-- | 74.7 KB |
| mempool.c | -rw-r--r-- | 10.5 KB |
| migrate.c | -rw-r--r-- | 47.5 KB |
| mincore.c | -rw-r--r-- | 7.8 KB |
| mlock.c | -rw-r--r-- | 22.3 KB |
| mm_init.c | -rw-r--r-- | 5.0 KB |
| mmap.c | -rw-r--r-- | 85.9 KB |
| mmu_context.c | -rw-r--r-- | 1.2 KB |
| mmu_notifier.c | -rw-r--r-- | 9.5 KB |
| mmzone.c | -rw-r--r-- | 2.4 KB |
| mprotect.c | -rw-r--r-- | 9.7 KB |
| mremap.c | -rw-r--r-- | 14.8 KB |
| msync.c | -rw-r--r-- | 2.4 KB |
| nobootmem.c | -rw-r--r-- | 10.5 KB |
| nommu.c | -rw-r--r-- | 53.1 KB |
| oom_kill.c | -rw-r--r-- | 19.6 KB |
| page-writeback.c | -rw-r--r-- | 75.5 KB |
| page_alloc.c | -rw-r--r-- | 178.8 KB |
| page_cgroup.c | -rw-r--r-- | 11.9 KB |
| page_io.c | -rw-r--r-- | 8.9 KB |
| page_isolation.c | -rw-r--r-- | 7.5 KB |
| pagewalk.c | -rw-r--r-- | 5.9 KB |
| percpu-km.c | -rw-r--r-- | 2.8 KB |
| percpu-vm.c | -rw-r--r-- | 12.9 KB |
| percpu.c | -rw-r--r-- | 57.1 KB |
| pgtable-generic.c | -rw-r--r-- | 5.2 KB |
| process_vm_access.c | -rw-r--r-- | 13.2 KB |
| quicklist.c | -rw-r--r-- | 2.4 KB |
| readahead.c | -rw-r--r-- | 16.0 KB |
| rmap.c | -rw-r--r-- | 50.7 KB |
| shmem.c | -rw-r--r-- | 78.6 KB |
| slab.c | -rw-r--r-- | 109.8 KB |
| slab.h | -rw-r--r-- | 7.4 KB |
| slab_common.c | -rw-r--r-- | 15.4 KB |
| slob.c | -rw-r--r-- | 15.7 KB |
| slub.c | -rw-r--r-- | 126.0 KB |
| sparse-vmemmap.c | -rw-r--r-- | 5.9 KB |
| sparse.c | -rw-r--r-- | 20.8 KB |
| swap.c | -rw-r--r-- | 26.3 KB |
| swap_state.c | -rw-r--r-- | 11.4 KB |
| swapfile.c | -rw-r--r-- | 76.5 KB |
| truncate.c | -rw-r--r-- | 19.5 KB |
| util.c | -rw-r--r-- | 9.8 KB |
| vmalloc.c | -rw-r--r-- | 67.9 KB |
| vmpressure.c | -rw-r--r-- | 11.7 KB |
| vmscan.c | -rw-r--r-- | 106.8 KB |
| vmstat.c | -rw-r--r-- | 34.9 KB |
| zbud.c | -rw-r--r-- | 15.9 KB |
| zswap.c | -rw-r--r-- | 24.1 KB |
Computing file changes ...
