* [syzbot] divide error in wb_update_dirty_ratelimit @ 2021-08-02 18:24 ` syzbot 0 siblings, 0 replies; 5+ messages in thread From: syzbot @ 2021-08-02 18:24 UTC (permalink / raw) To: akpm, linux-kernel, linux-mm, syzkaller-bugs Hello, syzbot found the following issue on: HEAD commit: 8d4b477da1a8 Add linux-next specific files for 20210730 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=128ede56300000 kernel config: https://syzkaller.appspot.com/x/.config?x=4adf4987f875c210 dashboard link: https://syzkaller.appspot.com/bug?extid=6a04d6ba849df9d81239 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+6a04d6ba849df9d81239@syzkaller.appspotmail.com divide error: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 10430 Comm: syz-executor.3 Not tainted 5.14.0-rc3-next-20210730-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:wb_update_dirty_ratelimit+0x18d/0x7d0 mm/page-writeback.c:1197 Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 05 00 00 4c 2b b5 30 02 00 00 49 8d 7f 58 31 d2 49 6b c6 64 <48> f7 f3 48 89 fa 48 89 04 24 48 b8 00 00 00 00 00 fc ff df 48 c1 RSP: 0018:ffffc9000551f750 EFLAGS: 00010206 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000fdb1000 RDX: 0000000000000000 RSI: 0000000000006377 RDI: ffffc9000551f9a0 RBP: ffff888089632060 R08: 0000000000000000 R09: ffffffff9023d363 R10: fffffbfff2047a6c R11: 0000000000000000 R12: 0000000000006400 R13: 000000000003c2b1 R14: 0000000000000000 R15: ffffc9000551f948 FS: 00007fdc4e708700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000206000bf CR3: 0000000073f41000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __wb_update_bandwidth+0x3d7/0x5a0 mm/page-writeback.c:1350 balance_dirty_pages+0x12ab/0x29d0 mm/page-writeback.c:1719 balance_dirty_pages_ratelimited+0xda2/0x1820 mm/page-writeback.c:1920 generic_perform_write+0x320/0x510 mm/filemap.c:3789 __generic_file_write_iter+0x24e/0x610 mm/filemap.c:3882 generic_file_write_iter+0xd7/0x220 mm/filemap.c:3914 fuse_cache_write_iter fs/fuse/file.c:1298 [inline] fuse_file_write_iter+0x56c/0xcd0 fs/fuse/file.c:1601 call_write_iter include/linux/fs.h:2152 [inline] new_sync_write+0x426/0x650 fs/read_write.c:518 vfs_write+0x75a/0xa40 fs/read_write.c:605 ksys_write+0x12d/0x250 fs/read_write.c:658 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665e9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdc4e708188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 RDX: 00000000fffffdef RSI: 00000000200000c0 RDI: 0000000000000006 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007fff2d6f27cf R14: 00007fdc4e708300 R15: 0000000000022000 Modules linked in: ---[ end trace 01891e5696647ce8 ]--- RIP: 0010:wb_update_dirty_ratelimit+0x18d/0x7d0 mm/page-writeback.c:1197 Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 05 00 00 4c 2b b5 30 02 00 00 49 8d 7f 58 31 d2 49 6b c6 64 <48> f7 f3 48 89 fa 48 89 04 24 48 b8 00 00 00 00 00 fc ff df 48 c1 RSP: 0018:ffffc9000551f750 EFLAGS: 00010206 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000fdb1000 RDX: 0000000000000000 RSI: 0000000000006377 RDI: ffffc9000551f9a0 RBP: ffff888089632060 R08: 0000000000000000 R09: ffffffff9023d363 R10: fffffbfff2047a6c R11: 0000000000000000 R12: 0000000000006400 R13: 000000000003c2b1 R14: 0000000000000000 R15: ffffc9000551f948 FS: 00007fdc4e708700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000206000bf CR3: 0000000073f41000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 --- This report 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 issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [syzbot] divide error in wb_update_dirty_ratelimit @ 2021-08-02 18:24 ` syzbot 0 siblings, 0 replies; 5+ messages in thread From: syzbot @ 2021-08-02 18:24 UTC (permalink / raw) To: akpm, linux-kernel, linux-mm, syzkaller-bugs Hello, syzbot found the following issue on: HEAD commit: 8d4b477da1a8 Add linux-next specific files for 20210730 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=128ede56300000 kernel config: https://syzkaller.appspot.com/x/.config?x=4adf4987f875c210 dashboard link: https://syzkaller.appspot.com/bug?extid=6a04d6ba849df9d81239 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+6a04d6ba849df9d81239@syzkaller.appspotmail.com divide error: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 10430 Comm: syz-executor.3 Not tainted 5.14.0-rc3-next-20210730-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:wb_update_dirty_ratelimit+0x18d/0x7d0 mm/page-writeback.c:1197 Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 05 00 00 4c 2b b5 30 02 00 00 49 8d 7f 58 31 d2 49 6b c6 64 <48> f7 f3 48 89 fa 48 89 04 24 48 b8 00 00 00 00 00 fc ff df 48 c1 RSP: 0018:ffffc9000551f750 EFLAGS: 00010206 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000fdb1000 RDX: 0000000000000000 RSI: 0000000000006377 RDI: ffffc9000551f9a0 RBP: ffff888089632060 R08: 0000000000000000 R09: ffffffff9023d363 R10: fffffbfff2047a6c R11: 0000000000000000 R12: 0000000000006400 R13: 000000000003c2b1 R14: 0000000000000000 R15: ffffc9000551f948 FS: 00007fdc4e708700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000206000bf CR3: 0000000073f41000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __wb_update_bandwidth+0x3d7/0x5a0 mm/page-writeback.c:1350 balance_dirty_pages+0x12ab/0x29d0 mm/page-writeback.c:1719 balance_dirty_pages_ratelimited+0xda2/0x1820 mm/page-writeback.c:1920 generic_perform_write+0x320/0x510 mm/filemap.c:3789 __generic_file_write_iter+0x24e/0x610 mm/filemap.c:3882 generic_file_write_iter+0xd7/0x220 mm/filemap.c:3914 fuse_cache_write_iter fs/fuse/file.c:1298 [inline] fuse_file_write_iter+0x56c/0xcd0 fs/fuse/file.c:1601 call_write_iter include/linux/fs.h:2152 [inline] new_sync_write+0x426/0x650 fs/read_write.c:518 vfs_write+0x75a/0xa40 fs/read_write.c:605 ksys_write+0x12d/0x250 fs/read_write.c:658 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665e9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdc4e708188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 RDX: 00000000fffffdef RSI: 00000000200000c0 RDI: 0000000000000006 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007fff2d6f27cf R14: 00007fdc4e708300 R15: 0000000000022000 Modules linked in: ---[ end trace 01891e5696647ce8 ]--- RIP: 0010:wb_update_dirty_ratelimit+0x18d/0x7d0 mm/page-writeback.c:1197 Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 05 00 00 4c 2b b5 30 02 00 00 49 8d 7f 58 31 d2 49 6b c6 64 <48> f7 f3 48 89 fa 48 89 04 24 48 b8 00 00 00 00 00 fc ff df 48 c1 RSP: 0018:ffffc9000551f750 EFLAGS: 00010206 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000fdb1000 RDX: 0000000000000000 RSI: 0000000000006377 RDI: ffffc9000551f9a0 RBP: ffff888089632060 R08: 0000000000000000 R09: ffffffff9023d363 R10: fffffbfff2047a6c R11: 0000000000000000 R12: 0000000000006400 R13: 000000000003c2b1 R14: 0000000000000000 R15: ffffc9000551f948 FS: 00007fdc4e708700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000206000bf CR3: 0000000073f41000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 --- This report 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 issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [syzbot] divide error in wb_update_dirty_ratelimit 2021-08-02 18:24 ` syzbot (?) @ 2021-08-02 20:31 ` Andrew Morton 2021-08-03 10:58 ` Jan Kara -1 siblings, 1 reply; 5+ messages in thread From: Andrew Morton @ 2021-08-02 20:31 UTC (permalink / raw) To: syzbot; +Cc: linux-kernel, linux-mm, syzkaller-bugs, Jan Kara On Mon, 02 Aug 2021 11:24:20 -0700 syzbot <syzbot+6a04d6ba849df9d81239@syzkaller.appspotmail.com> wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 8d4b477da1a8 Add linux-next specific files for 20210730 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=128ede56300000 > kernel config: https://syzkaller.appspot.com/x/.config?x=4adf4987f875c210 > dashboard link: https://syzkaller.appspot.com/bug?extid=6a04d6ba849df9d81239 > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+6a04d6ba849df9d81239@syzkaller.appspotmail.com > > divide error: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 10430 Comm: syz-executor.3 Not tainted 5.14.0-rc3-next-20210730-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:wb_update_dirty_ratelimit+0x18d/0x7d0 mm/page-writeback.c:1197 Thanks. Presumably wb_update_dirty_ratelimit() was passed elapsed==0. Jan, could your changes have caused this? > Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 05 00 00 4c 2b b5 30 02 00 00 49 8d 7f 58 31 d2 49 6b c6 64 <48> f7 f3 48 89 fa 48 89 04 24 48 b8 00 00 00 00 00 fc ff df 48 c1 > RSP: 0018:ffffc9000551f750 EFLAGS: 00010206 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000fdb1000 > RDX: 0000000000000000 RSI: 0000000000006377 RDI: ffffc9000551f9a0 > RBP: ffff888089632060 R08: 0000000000000000 R09: ffffffff9023d363 > R10: fffffbfff2047a6c R11: 0000000000000000 R12: 0000000000006400 > R13: 000000000003c2b1 R14: 0000000000000000 R15: ffffc9000551f948 > FS: 00007fdc4e708700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000206000bf CR3: 0000000073f41000 CR4: 00000000001506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > __wb_update_bandwidth+0x3d7/0x5a0 mm/page-writeback.c:1350 > balance_dirty_pages+0x12ab/0x29d0 mm/page-writeback.c:1719 > balance_dirty_pages_ratelimited+0xda2/0x1820 mm/page-writeback.c:1920 > generic_perform_write+0x320/0x510 mm/filemap.c:3789 > __generic_file_write_iter+0x24e/0x610 mm/filemap.c:3882 > generic_file_write_iter+0xd7/0x220 mm/filemap.c:3914 > fuse_cache_write_iter fs/fuse/file.c:1298 [inline] > fuse_file_write_iter+0x56c/0xcd0 fs/fuse/file.c:1601 > call_write_iter include/linux/fs.h:2152 [inline] > new_sync_write+0x426/0x650 fs/read_write.c:518 > vfs_write+0x75a/0xa40 fs/read_write.c:605 > ksys_write+0x12d/0x250 fs/read_write.c:658 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x4665e9 > Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007fdc4e708188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 > RDX: 00000000fffffdef RSI: 00000000200000c0 RDI: 0000000000000006 > RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 > R13: 00007fff2d6f27cf R14: 00007fdc4e708300 R15: 0000000000022000 > Modules linked in: > ---[ end trace 01891e5696647ce8 ]--- > RIP: 0010:wb_update_dirty_ratelimit+0x18d/0x7d0 mm/page-writeback.c:1197 > Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 05 00 00 4c 2b b5 30 02 00 00 49 8d 7f 58 31 d2 49 6b c6 64 <48> f7 f3 48 89 fa 48 89 04 24 48 b8 00 00 00 00 00 fc ff df 48 c1 > RSP: 0018:ffffc9000551f750 EFLAGS: 00010206 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000fdb1000 > RDX: 0000000000000000 RSI: 0000000000006377 RDI: ffffc9000551f9a0 > RBP: ffff888089632060 R08: 0000000000000000 R09: ffffffff9023d363 > R10: fffffbfff2047a6c R11: 0000000000000000 R12: 0000000000006400 > R13: 000000000003c2b1 R14: 0000000000000000 R15: ffffc9000551f948 > FS: 00007fdc4e708700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000206000bf CR3: 0000000073f41000 CR4: 00000000001506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [syzbot] divide error in wb_update_dirty_ratelimit 2021-08-02 20:31 ` Andrew Morton @ 2021-08-03 10:58 ` Jan Kara 2021-08-03 12:32 ` Jan Kara 0 siblings, 1 reply; 5+ messages in thread From: Jan Kara @ 2021-08-03 10:58 UTC (permalink / raw) To: Andrew Morton; +Cc: syzbot, linux-kernel, linux-mm, syzkaller-bugs, Jan Kara On Mon 02-08-21 13:31:06, Andrew Morton wrote: > On Mon, 02 Aug 2021 11:24:20 -0700 syzbot <syzbot+6a04d6ba849df9d81239@syzkaller.appspotmail.com> wrote: > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 8d4b477da1a8 Add linux-next specific files for 20210730 > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=128ede56300000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=4adf4987f875c210 > > dashboard link: https://syzkaller.appspot.com/bug?extid=6a04d6ba849df9d81239 > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+6a04d6ba849df9d81239@syzkaller.appspotmail.com > > > > divide error: 0000 [#1] PREEMPT SMP KASAN > > CPU: 0 PID: 10430 Comm: syz-executor.3 Not tainted 5.14.0-rc3-next-20210730-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > RIP: 0010:wb_update_dirty_ratelimit+0x18d/0x7d0 mm/page-writeback.c:1197 > > Thanks. > > Presumably wb_update_dirty_ratelimit() was passed elapsed==0. Jan, > could your changes have caused this? Right, they could have if wb_update_bandwidth_workfn() got called in the same jiffie as some other update. Thanks for letting me know. I'll send a fix. Honza > > Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 05 00 00 4c 2b b5 30 02 00 00 49 8d 7f 58 31 d2 49 6b c6 64 <48> f7 f3 48 89 fa 48 89 04 24 48 b8 00 00 00 00 00 fc ff df 48 c1 > > RSP: 0018:ffffc9000551f750 EFLAGS: 00010206 > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000fdb1000 > > RDX: 0000000000000000 RSI: 0000000000006377 RDI: ffffc9000551f9a0 > > RBP: ffff888089632060 R08: 0000000000000000 R09: ffffffff9023d363 > > R10: fffffbfff2047a6c R11: 0000000000000000 R12: 0000000000006400 > > R13: 000000000003c2b1 R14: 0000000000000000 R15: ffffc9000551f948 > > FS: 00007fdc4e708700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00000000206000bf CR3: 0000000073f41000 CR4: 00000000001506f0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > __wb_update_bandwidth+0x3d7/0x5a0 mm/page-writeback.c:1350 > > balance_dirty_pages+0x12ab/0x29d0 mm/page-writeback.c:1719 > > balance_dirty_pages_ratelimited+0xda2/0x1820 mm/page-writeback.c:1920 > > generic_perform_write+0x320/0x510 mm/filemap.c:3789 > > __generic_file_write_iter+0x24e/0x610 mm/filemap.c:3882 > > generic_file_write_iter+0xd7/0x220 mm/filemap.c:3914 > > fuse_cache_write_iter fs/fuse/file.c:1298 [inline] > > fuse_file_write_iter+0x56c/0xcd0 fs/fuse/file.c:1601 > > call_write_iter include/linux/fs.h:2152 [inline] > > new_sync_write+0x426/0x650 fs/read_write.c:518 > > vfs_write+0x75a/0xa40 fs/read_write.c:605 > > ksys_write+0x12d/0x250 fs/read_write.c:658 > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > RIP: 0033:0x4665e9 > > Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 > > RSP: 002b:00007fdc4e708188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > > RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 > > RDX: 00000000fffffdef RSI: 00000000200000c0 RDI: 0000000000000006 > > RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 > > R13: 00007fff2d6f27cf R14: 00007fdc4e708300 R15: 0000000000022000 > > Modules linked in: > > ---[ end trace 01891e5696647ce8 ]--- > > RIP: 0010:wb_update_dirty_ratelimit+0x18d/0x7d0 mm/page-writeback.c:1197 > > Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 05 00 00 4c 2b b5 30 02 00 00 49 8d 7f 58 31 d2 49 6b c6 64 <48> f7 f3 48 89 fa 48 89 04 24 48 b8 00 00 00 00 00 fc ff df 48 c1 > > RSP: 0018:ffffc9000551f750 EFLAGS: 00010206 > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000fdb1000 > > RDX: 0000000000000000 RSI: 0000000000006377 RDI: ffffc9000551f9a0 > > RBP: ffff888089632060 R08: 0000000000000000 R09: ffffffff9023d363 > > R10: fffffbfff2047a6c R11: 0000000000000000 R12: 0000000000006400 > > R13: 000000000003c2b1 R14: 0000000000000000 R15: ffffc9000551f948 > > FS: 00007fdc4e708700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00000000206000bf CR3: 0000000073f41000 CR4: 00000000001506f0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > -- Jan Kara <jack@suse.com> SUSE Labs, CR ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [syzbot] divide error in wb_update_dirty_ratelimit 2021-08-03 10:58 ` Jan Kara @ 2021-08-03 12:32 ` Jan Kara 0 siblings, 0 replies; 5+ messages in thread From: Jan Kara @ 2021-08-03 12:32 UTC (permalink / raw) To: Andrew Morton; +Cc: syzbot, linux-kernel, linux-mm, syzkaller-bugs, Jan Kara [-- Attachment #1: Type: text/plain, Size: 5504 bytes --] On Tue 03-08-21 12:58:12, Jan Kara wrote: > On Mon 02-08-21 13:31:06, Andrew Morton wrote: > > On Mon, 02 Aug 2021 11:24:20 -0700 syzbot <syzbot+6a04d6ba849df9d81239@syzkaller.appspotmail.com> wrote: > > > > > Hello, > > > > > > syzbot found the following issue on: > > > > > > HEAD commit: 8d4b477da1a8 Add linux-next specific files for 20210730 > > > git tree: linux-next > > > console output: https://syzkaller.appspot.com/x/log.txt?x=128ede56300000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=4adf4987f875c210 > > > dashboard link: https://syzkaller.appspot.com/bug?extid=6a04d6ba849df9d81239 > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 > > > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > Reported-by: syzbot+6a04d6ba849df9d81239@syzkaller.appspotmail.com > > > > > > divide error: 0000 [#1] PREEMPT SMP KASAN > > > CPU: 0 PID: 10430 Comm: syz-executor.3 Not tainted 5.14.0-rc3-next-20210730-syzkaller #0 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > > RIP: 0010:wb_update_dirty_ratelimit+0x18d/0x7d0 mm/page-writeback.c:1197 > > > > Thanks. > > > > Presumably wb_update_dirty_ratelimit() was passed elapsed==0. Jan, > > could your changes have caused this? > > Right, they could have if wb_update_bandwidth_workfn() got called in the > same jiffie as some other update. Thanks for letting me know. I'll send a > fix. Attached patch should fix the problem. Can you add this as a fixup for "writeback: Fix bandwidth estimate for spiky workload" please? Thanks! Honza > > > Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 05 00 00 4c 2b b5 30 02 00 00 49 8d 7f 58 31 d2 49 6b c6 64 <48> f7 f3 48 89 fa 48 89 04 24 48 b8 00 00 00 00 00 fc ff df 48 c1 > > > RSP: 0018:ffffc9000551f750 EFLAGS: 00010206 > > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000fdb1000 > > > RDX: 0000000000000000 RSI: 0000000000006377 RDI: ffffc9000551f9a0 > > > RBP: ffff888089632060 R08: 0000000000000000 R09: ffffffff9023d363 > > > R10: fffffbfff2047a6c R11: 0000000000000000 R12: 0000000000006400 > > > R13: 000000000003c2b1 R14: 0000000000000000 R15: ffffc9000551f948 > > > FS: 00007fdc4e708700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: 00000000206000bf CR3: 0000000073f41000 CR4: 00000000001506f0 > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > Call Trace: > > > __wb_update_bandwidth+0x3d7/0x5a0 mm/page-writeback.c:1350 > > > balance_dirty_pages+0x12ab/0x29d0 mm/page-writeback.c:1719 > > > balance_dirty_pages_ratelimited+0xda2/0x1820 mm/page-writeback.c:1920 > > > generic_perform_write+0x320/0x510 mm/filemap.c:3789 > > > __generic_file_write_iter+0x24e/0x610 mm/filemap.c:3882 > > > generic_file_write_iter+0xd7/0x220 mm/filemap.c:3914 > > > fuse_cache_write_iter fs/fuse/file.c:1298 [inline] > > > fuse_file_write_iter+0x56c/0xcd0 fs/fuse/file.c:1601 > > > call_write_iter include/linux/fs.h:2152 [inline] > > > new_sync_write+0x426/0x650 fs/read_write.c:518 > > > vfs_write+0x75a/0xa40 fs/read_write.c:605 > > > ksys_write+0x12d/0x250 fs/read_write.c:658 > > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > > RIP: 0033:0x4665e9 > > > Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 > > > RSP: 002b:00007fdc4e708188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > > > RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 > > > RDX: 00000000fffffdef RSI: 00000000200000c0 RDI: 0000000000000006 > > > RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 > > > R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 > > > R13: 00007fff2d6f27cf R14: 00007fdc4e708300 R15: 0000000000022000 > > > Modules linked in: > > > ---[ end trace 01891e5696647ce8 ]--- > > > RIP: 0010:wb_update_dirty_ratelimit+0x18d/0x7d0 mm/page-writeback.c:1197 > > > Code: 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 05 00 00 4c 2b b5 30 02 00 00 49 8d 7f 58 31 d2 49 6b c6 64 <48> f7 f3 48 89 fa 48 89 04 24 48 b8 00 00 00 00 00 fc ff df 48 c1 > > > RSP: 0018:ffffc9000551f750 EFLAGS: 00010206 > > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000fdb1000 > > > RDX: 0000000000000000 RSI: 0000000000006377 RDI: ffffc9000551f9a0 > > > RBP: ffff888089632060 R08: 0000000000000000 R09: ffffffff9023d363 > > > R10: fffffbfff2047a6c R11: 0000000000000000 R12: 0000000000006400 > > > R13: 000000000003c2b1 R14: 0000000000000000 R15: ffffc9000551f948 > > > FS: 00007fdc4e708700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: 00000000206000bf CR3: 0000000073f41000 CR4: 00000000001506f0 > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > -- > Jan Kara <jack@suse.com> > SUSE Labs, CR -- Jan Kara <jack@suse.com> SUSE Labs, CR [-- Attachment #2: 0001-writeback-Avoid-division-by-0-in-wb_update_dirty_rat.patch --] [-- Type: text/x-patch, Size: 1263 bytes --] From 9c16cd6b3353e39c0d596a7baf9f9067aa1a05b5 Mon Sep 17 00:00:00 2001 From: Jan Kara <jack@suse.cz> Date: Tue, 3 Aug 2021 14:24:32 +0200 Subject: [PATCH] writeback: Avoid division by 0 in wb_update_dirty_ratelimit() Fixup patch "writeback: Fix bandwidth estimate for spiky workload" which introduced possibility of __wb_update_bandwidth() getting called at a moment when 'elapsed' evaluates to 0. Signed-off-by: Jan Kara <jack@suse.cz> --- mm/page-writeback.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index d55a3a7411b3..b2fa9f20c764 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1342,7 +1342,13 @@ static void __wb_update_bandwidth(struct dirty_throttle_control *gdtc, unsigned long written; spin_lock(&wb->list_lock); - elapsed = now - wb->bw_time_stamp; + /* + * Lockless checks for elapsed time are racy and delayed update after + * IO completion doesn't do it at all (to make sure written pages are + * accounted reasonably quickly). Make sure elapsed >= 1 to avoid + * division errors. + */ + elapsed = max(now - wb->bw_time_stamp, 1UL); dirtied = percpu_counter_read(&wb->stat[WB_DIRTIED]); written = wb_stat_sum(wb, WB_WRITTEN); -- 2.26.2 ^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-08-03 12:32 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-08-02 18:24 [syzbot] divide error in wb_update_dirty_ratelimit syzbot 2021-08-02 18:24 ` syzbot 2021-08-02 20:31 ` Andrew Morton 2021-08-03 10:58 ` Jan Kara 2021-08-03 12:32 ` Jan Kara
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