Our syzkaller trigger the "BUG_ON(!list_empty(&inode->i_wb_list))" in clear_inode: [ 292.016156] ------------[ cut here ]------------ [ 292.017144] kernel BUG at fs/inode.c:519! [ 292.017860] Internal error: Oops - BUG: 0 [#1] SMP [ 292.018741] Dumping ftrace buffer: [ 292.019577] (ftrace buffer empty) [ 292.020430] Modules linked in: [ 292.021748] Process syz-executor.0 (pid: 249, stack limit = 0x00000000a12409d7) [ 292.023719] CPU: 1 PID: 249 Comm: syz-executor.0 Not tainted 4.19.95 [ 292.025206] Hardware name: linux,dummy-virt (DT) [ 292.026176] pstate: 80000005 (Nzcv daif -PAN -UAO) [ 292.027244] pc : clear_inode+0x280/0x2a8 [ 292.028045] lr : clear_inode+0x280/0x2a8 [ 292.028877] sp : ffff8003366c7950 [ 292.029582] x29: ffff8003366c7950 x28: 0000000000000000 [ 292.030570] x27: ffff80032b5f4708 x26: ffff80032b5f4678 [ 292.031863] x25: ffff80036ae6b300 x24: ffff8003689254d0 [ 292.032902] x23: ffff80036ae69d80 x22: 0000000000033cc8 [ 292.033928] x21: 0000000000000000 x20: ffff80032b5f47a0 [ 292.034941] x19: ffff80032b5f4678 x18: 0000000000000000 [ 292.035958] x17: 0000000000000000 x16: 0000000000000000 [ 292.037102] x15: 0000000000000000 x14: 0000000000000000 [ 292.038103] x13: 0000000000000004 x12: 0000000000000000 [ 292.039137] x11: 1ffff00066cd8f52 x10: 1ffff00066cd8ec8 [ 292.040216] x9 : dfff200000000000 x8 : ffff10006ac1e86a [ 292.041432] x7 : dfff200000000000 x6 : ffff100066cd8f1e [ 292.042516] x5 : dfff200000000000 x4 : ffff80032b5f47a0 [ 292.043525] x3 : ffff200008000000 x2 : ffff200009867000 [ 292.044560] x1 : ffff8003366bb000 x0 : 0000000000000000 [ 292.045569] Call trace: [ 292.046083] clear_inode+0x280/0x2a8 [ 292.046828] ext4_clear_inode+0x38/0xe8 [ 292.047593] ext4_free_inode+0x130/0xc68 [ 292.048383] ext4_evict_inode+0xb20/0xcb8 [ 292.049162] evict+0x1a8/0x3c0 [ 292.049761] iput+0x344/0x460 [ 292.050350] do_unlinkat+0x260/0x410 [ 292.051042] __arm64_sys_unlinkat+0x6c/0xc0 [ 292.051846] el0_svc_common+0xdc/0x3b0 [ 292.052570] el0_svc_handler+0xf8/0x160 [ 292.053303] el0_svc+0x10/0x218 [ 292.053908] Code: 9413f4a9 d503201f f90017b6 97f4d5b1 (d4210000) [ 292.055471] ---[ end trace 01b339dd07795f8d ]--- [ 292.056443] Kernel panic - not syncing: Fatal exception [ 292.057488] SMP: stopping secondary CPUs [ 292.058419] Dumping ftrace buffer: [ 292.059078] (ftrace buffer empty) [ 292.059756] Kernel Offset: disabled [ 292.060443] CPU features: 0x10,a1006000 [ 292.061195] Memory Limit: none [ 292.061794] Rebooting in 86400 seconds.. Crash of this problem show that someone call __munlock_pagevec to clear page LRU. #0 [ffff80035f02f4c0] __switch_to at ffff20000808d020 #1 [ffff80035f02f4f0] __schedule at ffff20000985102c #2 [ffff80035f02f5e0] schedule at ffff200009851d1c #3 [ffff80035f02f600] io_schedule at ffff2000098525c0 #4 [ffff80035f02f620] __lock_page at ffff20000842d2d4 #5 [ffff80035f02f710] __munlock_pagevec at ffff2000084c4600 #6 [ffff80035f02f870] munlock_vma_pages_range at ffff2000084c5928 #7 [ffff80035f02fa60] do_munmap at ffff2000084cbdf4 #8 [ffff80035f02faf0] mmap_region at ffff2000084ce20c #9 [ffff80035f02fb90] do_mmap at ffff2000084cf018 So memory_failure will call identify_page_state without wait_on_page_writeback. And after generic_truncate_error_page clear the mapping of this page. end_page_writeback won't call sb_clear_inode_writeback to clear inode->i_wb_list. That will trigger BUG_ON in clear_inode! Fix it by move the wait_on_page_writeback before check of LRU. Signed-off-by: yangerkun <yangerkun@xxxxxxxxxx> --- mm/memory-failure.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index bd3945446d47..9870a22800d9 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1527,15 +1527,15 @@ int memory_failure(unsigned long pfn, int flags) return 0; } - if (!PageTransTail(p) && !PageLRU(p)) - goto identify_page_state; - /* * It's very difficult to mess with pages currently under IO * and in many cases impossible, so we just avoid it here. */ wait_on_page_writeback(p); + if (!PageTransTail(p) && !PageLRU(p)) + goto identify_page_state; + /* * Now take care of user space mappings. * Abort on fail: __delete_from_page_cache() assumes unmapped page. -- 2.25.4
