On 11/06/2014 11:27 PM, Sasha Levin wrote: > Hi all, > > While fuzzing with trinity inside a KVM tools guest running the latest -next > kernel, I've stumbled on the following spew: > > [ 1441.564471] BUG: Bad page state in process trinity-c612 pfn:12593a > [ 1441.564476] page:ffffea0006e175c0 count:0 mapcount:0 mapping: (null) index: > 0x49 > [ 1441.564488] flags: 0xafffff8028000c(referenced|uptodate|swapbacked|mlocked) > [ 1441.564491] page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set > [ 1441.564493] bad because of flags: > [ 1441.564498] flags: 0x200000(mlocked) > [ 1441.564503] Modules linked in: > [ 1441.564511] CPU: 2 PID: 11657 Comm: trinity-c612 Not tainted 3.18.0-rc3-next-20141106-sasha-00054-g09b7ccf-dirty #1447 > [ 1441.564519] 0000000000000000 0000000000000000 1ffffffff3b44e48 ffff8805c969b868 > [ 1441.564526] ffffffff9c085024 0000000000000000 ffffea0006e175c0 ffff8805c969b898 > [ 1441.564532] ffffffff925fd0a1 ffffea0006e17628 dfffe90000000000 0000000000000000 > [ 1441.564534] Call Trace: > [ 1441.568496] dump_stack (lib/dump_stack.c:52) > [ 1441.568516] bad_page (mm/page_alloc.c:338) > [ 1441.568523] free_pages_prepare (mm/page_alloc.c:649 mm/page_alloc.c:755) > [ 1441.568531] free_hot_cold_page (mm/page_alloc.c:1436) > [ 1441.568541] free_hot_cold_page_list (mm/page_alloc.c:1482 (discriminator 3)) > [ 1441.568555] release_pages (mm/swap.c:961) > [ 1441.568566] __pagevec_release (include/linux/pagevec.h:44 mm/swap.c:978) > [ 1441.568579] shmem_undo_range (include/linux/pagevec.h:69 mm/shmem.c:451) > [ 1441.568591] shmem_truncate_range (mm/shmem.c:546) > [ 1441.568599] shmem_fallocate (include/linux/spinlock.h:309 mm/shmem.c:2092) > [ 1441.568612] ? __sb_start_write (fs/super.c:1208) > [ 1441.568622] ? __sb_start_write (fs/super.c:1208) > [ 1441.568633] do_fallocate (fs/open.c:297) > [ 1441.568648] SyS_madvise (mm/madvise.c:332 mm/madvise.c:381 mm/madvise.c:531 mm/madvise.c:462) > [ 1441.568660] ? syscall_trace_enter_phase1 (include/linux/context_tracking.h:27 arch/x86/kernel/ptrace.c:1486) > [ 1441.568672] tracesys_phase2 (arch/x86/kernel/entry_64.S:529) > > I'm slightly confused here, because the page is mapcount==0, not LOCKED but still MLOCKED... So I got this as well: [ 1026.988043] BUG: Bad page state in process trinity-c374 pfn:23f70 [ 1026.989684] page:ffffea0000b3d300 count:0 mapcount:0 mapping: (null) index:0x5b [ 1026.991151] flags: 0x1fffff8028000c(referenced|uptodate|swapbacked|mlocked) [ 1026.992410] page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set [ 1026.993479] bad because of flags: [ 1026.994125] flags: 0x200000(mlocked) [ 1026.994816] Modules linked in: [ 1026.995378] CPU: 7 PID: 7879 Comm: trinity-c374 Not tainted 3.18.0-rc4-next-20141113-sasha-00047-gd1763ce-dirty #1455 [ 1026.996123] FAULT_INJECTION: forcing a failure. [ 1026.996123] name failslab, interval 100, probability 30, space 0, times -1 [ 1026.999050] 0000000000000000 0000000000000000 0000000000b3d300 ffff88061295bbd8 [ 1027.000676] ffffffff92f71097 0000000000000000 ffffea0000b3d300 ffff88061295bc08 [ 1027.002020] ffffffff8197ef7a ffffea0000b3d300 ffffffff942dd148 dfffe90000000000 [ 1027.003359] Call Trace: [ 1027.003831] dump_stack (lib/dump_stack.c:52) [ 1027.004725] bad_page (mm/page_alloc.c:338) [ 1027.005623] free_pages_prepare (mm/page_alloc.c:657 mm/page_alloc.c:763) [ 1027.006761] free_hot_cold_page (mm/page_alloc.c:1438) [ 1027.007772] ? __page_cache_release (mm/swap.c:66) [ 1027.008815] put_page (mm/swap.c:270) [ 1027.009665] page_cache_pipe_buf_release (fs/splice.c:93) [ 1027.010888] __splice_from_pipe (fs/splice.c:784 fs/splice.c:886) [ 1027.011917] ? might_fault (./arch/x86/include/asm/current.h:14 mm/memory.c:3734) [ 1027.012856] ? pipe_lock (fs/pipe.c:69) [ 1027.013728] ? write_pipe_buf (fs/splice.c:1534) [ 1027.014756] vmsplice_to_user (fs/splice.c:1574) [ 1027.015725] ? rcu_read_lock_held (kernel/rcu/update.c:169) [ 1027.016757] ? __fget_light (include/linux/fdtable.h:80 fs/file.c:684) [ 1027.017782] SyS_vmsplice (fs/splice.c:1656 fs/splice.c:1639) [ 1027.018863] tracesys_phase2 (arch/x86/kernel/entry_64.S:529) Which makes me suspect I blamed shmem for nothing. Thanks, Sasha -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>