在 2021/5/14 13:21, HORIGUCHI NAOYA(堀口 直也) 写道:
On Tue, May 11, 2021 at 03:03:29PM +0800, yangerkun wrote:
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>
The if-block of "goto identify_page_state" was introduced by commit
0bc1f8b0682c ("hwpoison: fix the handling path of the victimized page frame
that belong to non-LRU"), and maybe the issue got visible on commit
6c60d2b5746c ("fs/fs-writeback.c: add a new writeback list for sync"),
which added inode->i_wb_list.
So you can add Fixes tag for either commit (maybe 0bc1f8b0682c?).
Thanks for your advise, I think we'd better add Fixes tag with
0bc1f8b0682c ("hwpoison: fix the handling path of the victimized page
frame that belong to non-LRU").
Thanks,
Kun.
Thanks,
Naoya Horiguchi
---
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
