All of lore.kernel.org
 help / color / mirror / Atom feed
* linux-next test error: WARNING in collapse_file
@ 2019-10-22 22:44 ` syzbot
  0 siblings, 0 replies; 3+ messages in thread
From: syzbot @ 2019-10-22 22:44 UTC (permalink / raw)
  To: akpm, hughd, jglisse, kirill.shutemov, linux-kernel, linux-mm,
	songliubraving, syzkaller-bugs, willy

Hello,

syzbot found the following crash on:

HEAD commit:    a722f75b Add linux-next specific files for 20191022
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=126aea5b600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=32434321999f01e9
dashboard link: https://syzkaller.appspot.com/bug?extid=667740df862911577d63
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+667740df862911577d63@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 1080 at mm/khugepaged.c:1643  
collapse_file+0x1f9d/0x4170 mm/khugepaged.c:1643
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 1080 Comm: khugepaged Not tainted 5.4.0-rc4-next-20191022 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x172/0x1f0 lib/dump_stack.c:113
  panic+0x2e3/0x75c kernel/panic.c:221
  __warn.cold+0x2f/0x35 kernel/panic.c:582
  report_bug+0x289/0x300 lib/bug.c:195
  fixup_bug arch/x86/kernel/traps.c:174 [inline]
  fixup_bug arch/x86/kernel/traps.c:169 [inline]
  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
  do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:collapse_file+0x1f9d/0x4170 mm/khugepaged.c:1643
Code: a1 c0 ff 31 c9 ba 01 00 00 00 4c 89 fe 48 8b bd c0 fe ff ff e8 e4 e9  
ec ff e9 b4 fd ff ff 4c 8b bd 88 fe ff ff e8 93 a1 c0 ff <0f> 0b 4c 8b a3  
50 ff ff ff c7 85 80 fe ff ff 00 00 00 00 e9 05 f6
RSP: 0018:ffff8880a818fad0 EFLAGS: 00010293
RAX: ffff8880a7dd8440 RBX: ffff8880a818fc88 RCX: ffffffff81b2b688
RDX: 0000000000000000 RSI: ffffffff81b2b9ad RDI: 0000000000000001
RBP: ffff8880a818fcb0 R08: ffff8880a7dd8440 R09: fffff940004942b9
R10: fffff940004942b8 R11: ffffea00024a15c7 R12: 0000000000000001
R13: ffffea0002383a08 R14: 0000000000000000 R15: ffffea0002338000
  khugepaged_scan_file mm/khugepaged.c:1881 [inline]
  khugepaged_scan_mm_slot mm/khugepaged.c:1979 [inline]
  khugepaged_do_scan mm/khugepaged.c:2063 [inline]
  khugepaged+0x2da9/0x4360 mm/khugepaged.c:2108
  kthread+0x361/0x430 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

^ permalink raw reply	[flat|nested] 3+ messages in thread
* linux-next test error: WARNING in collapse_file
@ 2019-10-22 22:44 ` syzbot
  0 siblings, 0 replies; 3+ messages in thread
From: syzbot @ 2019-10-22 22:44 UTC (permalink / raw)
  To: akpm, hughd, jglisse, kirill.shutemov, linux-kernel, linux-mm,
	songliubraving, syzkaller-bugs, willy

Hello,

syzbot found the following crash on:

HEAD commit:    a722f75b Add linux-next specific files for 20191022
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=126aea5b600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=32434321999f01e9
dashboard link: https://syzkaller.appspot.com/bug?extid=667740df862911577d63
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+667740df862911577d63@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 1080 at mm/khugepaged.c:1643  
collapse_file+0x1f9d/0x4170 mm/khugepaged.c:1643
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 1080 Comm: khugepaged Not tainted 5.4.0-rc4-next-20191022 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x172/0x1f0 lib/dump_stack.c:113
  panic+0x2e3/0x75c kernel/panic.c:221
  __warn.cold+0x2f/0x35 kernel/panic.c:582
  report_bug+0x289/0x300 lib/bug.c:195
  fixup_bug arch/x86/kernel/traps.c:174 [inline]
  fixup_bug arch/x86/kernel/traps.c:169 [inline]
  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
  do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:collapse_file+0x1f9d/0x4170 mm/khugepaged.c:1643
Code: a1 c0 ff 31 c9 ba 01 00 00 00 4c 89 fe 48 8b bd c0 fe ff ff e8 e4 e9  
ec ff e9 b4 fd ff ff 4c 8b bd 88 fe ff ff e8 93 a1 c0 ff <0f> 0b 4c 8b a3  
50 ff ff ff c7 85 80 fe ff ff 00 00 00 00 e9 05 f6
RSP: 0018:ffff8880a818fad0 EFLAGS: 00010293
RAX: ffff8880a7dd8440 RBX: ffff8880a818fc88 RCX: ffffffff81b2b688
RDX: 0000000000000000 RSI: ffffffff81b2b9ad RDI: 0000000000000001
RBP: ffff8880a818fcb0 R08: ffff8880a7dd8440 R09: fffff940004942b9
R10: fffff940004942b8 R11: ffffea00024a15c7 R12: 0000000000000001
R13: ffffea0002383a08 R14: 0000000000000000 R15: ffffea0002338000
  khugepaged_scan_file mm/khugepaged.c:1881 [inline]
  khugepaged_scan_mm_slot mm/khugepaged.c:1979 [inline]
  khugepaged_do_scan mm/khugepaged.c:2063 [inline]
  khugepaged+0x2da9/0x4360 mm/khugepaged.c:2108
  kthread+0x361/0x430 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.


^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: linux-next test error: WARNING in collapse_file
  2019-10-22 22:44 ` syzbot
  (?)
@ 2019-10-22 23:10 ` Andrew Morton
  -1 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2019-10-22 23:10 UTC (permalink / raw)
  To: syzbot
  Cc: hughd, jglisse, kirill.shutemov, linux-kernel, linux-mm,
	songliubraving, syzkaller-bugs, willy

On Tue, 22 Oct 2019 15:44:12 -0700 syzbot <syzbot+667740df862911577d63@syzkaller.appspotmail.com> wrote:

> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    a722f75b Add linux-next specific files for 20191022
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=126aea5b600000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=32434321999f01e9
> dashboard link: https://syzkaller.appspot.com/bug?extid=667740df862911577d63
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+667740df862911577d63@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 1080 at mm/khugepaged.c:1643  
> collapse_file+0x1f9d/0x4170 mm/khugepaged.c:1643
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 1 PID: 1080 Comm: khugepaged Not tainted 5.4.0-rc4-next-20191022 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
> Google 01/01/2011
> Call Trace:
>   __dump_stack lib/dump_stack.c:77 [inline]
>   dump_stack+0x172/0x1f0 lib/dump_stack.c:113
>   panic+0x2e3/0x75c kernel/panic.c:221
>   __warn.cold+0x2f/0x35 kernel/panic.c:582
>   report_bug+0x289/0x300 lib/bug.c:195
>   fixup_bug arch/x86/kernel/traps.c:174 [inline]
>   fixup_bug arch/x86/kernel/traps.c:169 [inline]
>   do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
>   do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
>   invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
> RIP: 0010:collapse_file+0x1f9d/0x4170 mm/khugepaged.c:1643
> Code: a1 c0 ff 31 c9 ba 01 00 00 00 4c 89 fe 48 8b bd c0 fe ff ff e8 e4 e9  
> ec ff e9 b4 fd ff ff 4c 8b bd 88 fe ff ff e8 93 a1 c0 ff <0f> 0b 4c 8b a3  
> 50 ff ff ff c7 85 80 fe ff ff 00 00 00 00 e9 05 f6
> RSP: 0018:ffff8880a818fad0 EFLAGS: 00010293
> RAX: ffff8880a7dd8440 RBX: ffff8880a818fc88 RCX: ffffffff81b2b688
> RDX: 0000000000000000 RSI: ffffffff81b2b9ad RDI: 0000000000000001
> RBP: ffff8880a818fcb0 R08: ffff8880a7dd8440 R09: fffff940004942b9
> R10: fffff940004942b8 R11: ffffea00024a15c7 R12: 0000000000000001
> R13: ffffea0002383a08 R14: 0000000000000000 R15: ffffea0002338000
>   khugepaged_scan_file mm/khugepaged.c:1881 [inline]
>   khugepaged_scan_mm_slot mm/khugepaged.c:1979 [inline]
>   khugepaged_do_scan mm/khugepaged.c:2063 [inline]
>   khugepaged+0x2da9/0x4360 mm/khugepaged.c:2108
>   kthread+0x361/0x430 kernel/kthread.c:255
>   ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Thanks.  This should be fixed in v4:


From: Song Liu <songliubraving@fb.com>
Subject: mmthp-recheck-each-page-before-collapsing-file-thp-v4

Trigger filemap_flush() for PageDirty() case.  This covers one-off
situation, where the file hasn't been flushed since first write.

Link: http://lkml.kernel.org/r/20191022191006.411277-1-songliubraving@fb.com
Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/khugepaged.c |   19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

--- a/mm/khugepaged.c~mmthp-recheck-each-page-before-collapsing-file-thp-v4
+++ a/mm/khugepaged.c
@@ -1636,11 +1636,20 @@ static void collapse_file(struct mm_stru
 			goto out_unlock;
 		}
 
-		/*
-		 * khugepaged should not try to collapse dirty pages for
-		 * file THP. Show warning if this somehow happens.
-		 */
-		if (WARN_ON_ONCE(!is_shmem && PageDirty(page))) {
+		if (!is_shmem && PageDirty(page)) {
+			/*
+			 * khugepaged only works on read-only fd, so this
+			 * page is dirty because it hasn't been flushed
+			 * since first write. There won't be new dirty
+			 * pages.
+			 *
+			 * Trigger async flush here and hope the writeback
+			 * is done when khugepaged revisits this page.
+			 *
+			 * This is a one-off situation. We are not forcing
+			 * writeback in loop.
+			 */
+			filemap_flush(mapping);
 			result = SCAN_FAIL;
 			goto out_unlock;
 		}
_


^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-10-22 23:11 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-10-22 22:44 linux-next test error: WARNING in collapse_file syzbot
2019-10-22 22:44 ` syzbot
2019-10-22 23:10 ` Andrew Morton

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.