Re: [inotify_read] BUG: unable to handle kernel paging request at ffff8800172f8000

[Jan Kara]

On Tue 07-11-17 18:28:27, Wu Fengguang wrote:
> FYI This bug trace also contains inotify_read().
> 
> [    3.187637] debug: unmapping init [mem 0xffff880001760000-0xffff8800017fffff]
> [    3.188582] debug: unmapping init [mem 0xffff880001b33000-0xffff880001bfffff]
> [    3.215019] x86/mm: Checked W+X mappings: passed, no W+X pages found.
> [    3.215815] rodata_test: all tests were successful
> mountall: Event failed
> [    3.365745] BUG: unable to handle kernel paging request at ffff8800172f8000
> [    3.366661] IP: slob_free+0x1c4/0x276
> [    3.367108] PGD 38c6067 P4D 38c6067 PUD 38c7067 PMD 1e747067 PTE 80000000172f8060
> [    3.367996] Oops: 0000 [#1] DEBUG_PAGEALLOC
> [    3.368505] Modules linked in:
> [    3.368876] CPU: 0 PID: 1 Comm: init Not tainted 4.14.0-rc8 #136
> [    3.369585] task: ffff8800002ec000 task.stack: ffffc90000008000
> [    3.370286] RIP: 0010:slob_free+0x1c4/0x276
> [    3.370781] RSP: 0018:ffffc9000000bd60 EFLAGS: 00010046
> [    3.371396] RAX: ffff8800172f7ffe RBX: ffff8800172f7fc0 RCX: 0000000000001420
> [    3.372230] RDX: ffff8800172f7000 RSI: ffffffff81e35608 RDI: ffff8800172f74f8
> [    3.373500] RBP: ffff8800172f7ffe R08: 0000000000000001 R09: 0000000000000001
> [    3.374781] R10: ffffc9000000bcb8 R11: 00000000ed37afc6 R12: ffff8800172f74f8
> [    3.375848] R13: 000000000000001f R14: 000000000000001f R15: 000000000000001f
> [    3.376699] FS:  00007fcb05cb1700(0000) GS:ffffffff81c2e000(0000) knlGS:0000000000000000
> [    3.377649] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    3.378334] CR2: ffff8800172f8000 CR3: 000000001727a000 CR4: 00000000000006b0
> [    3.379167] Call Trace:
> [    3.379481]  inotify_read+0x1d2/0x29c
> [    3.379928]  ? prepare_to_wait_exclusive+0x64/0x64
> [    3.380495]  ? SYSC_inotify_init1+0x195/0x195
> [    3.381134]  __vfs_read+0x45/0xef
> [    3.381673]  ? __do_page_fault+0x449/0x5af
> [    3.382328]  ? lock_release+0x26c/0x2cd
> [    3.382935]  vfs_read+0xba/0x100
> [    3.383457]  SyS_read+0x5b/0xa1
> [    3.383959]  entry_SYSCALL_64_fastpath+0x1f/0xbd
> [    3.384685] RIP: 0033:0x7fcb05222d10
> [    3.385247] RSP: 002b:00007fff14b56018 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> [    3.386427] RAX: ffffffffffffffda RBX: 0000000000000046 RCX: 00007fcb05222d10
> [    3.387532] RDX: 0000000000002000 RSI: 000055e4667a3620 RDI: 0000000000000005
> [    3.388633] RBP: 0000000000002041 R08: 0000000000000000 R09: 0000000001000000
> [    3.389736] R10: 0000000000000000 R11: 0000000000000246 R12: 00007fcb05005778
> [    3.390838] R13: 0000000000002030 R14: 000055e4667a35e0 R15: 000000000001b9e1
> [    3.391947] Code: 89 ec e8 d1 f5 ff ff 48 39 c3 48 89 c5 77 ed 4c 89 e7 e8 c1 f5 ff ff a9 ff 0f 00 00 74 31 49 0f bf c5 48 8d 04 43 48 39 e8 75 24 <8b> 45 00 41 be 01 00 00 00 48 89 ef 66 85 c0 44 0f 4f f0 45 01 
> [    3.394915] RIP: slob_free+0x1c4/0x276 RSP: ffffc9000000bd60
> [    3.395797] CR2: ffff8800172f8000
> [    3.396328] ---[ end trace 66f2347dc7fa73e0 ]---
> [    3.397046] Kernel panic - not syncing: Fatal exception
> 
> Attached the full dmesg and kconfig.

Ok, I assume this is still valid even though previous KASAN report need not
be? I'm not sure if this could be inotify related though... Possibly if
double-free could trigger this in SLOB but then we should see issues also
with SLAB or SLUB.

								Honza
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR