Re: possible deadlock in __wake_up_common_lock

2019-01-08 Thread Peter Zijlstra
On Wed, Jan 02, 2019 at 01:51:01PM +0100, Vlastimil Babka wrote: > > syz-executor0/8529 is trying to acquire lock: > > 5e7fb829 (&pgdat->kswapd_wait){}, at: > > __wake_up_common_lock+0x19e/0x330 kernel/sched/wait.c:120 > > From the backtrace at the end of report I see it's coming fr

Re: possible deadlock in __wake_up_common_lock

2019-01-07 Thread Peter Zijlstra
On Mon, Jan 07, 2019 at 10:29:21PM +0100, Peter Zijlstra wrote: > On Mon, Jan 07, 2019 at 03:46:27PM -0500, Johannes Weiner wrote: > > Hm, so the splat says this: > > > > wakeups take the pi lock > > pi lock holders take the rq lock > > rq lock holders take the timer base lock (thanks psi) > > tim

Re: possible deadlock in __wake_up_common_lock

2019-01-07 Thread Peter Zijlstra
On Mon, Jan 07, 2019 at 03:46:27PM -0500, Johannes Weiner wrote: > Hm, so the splat says this: > > wakeups take the pi lock > pi lock holders take the rq lock > rq lock holders take the timer base lock (thanks psi) > timer base lock holders take the zone lock (thanks kasan) > problem: now a zone l

Re: possible deadlock in __wake_up_common_lock

2019-01-07 Thread Johannes Weiner
On Mon, Jan 07, 2019 at 10:52:17AM +0100, Peter Zijlstra wrote: > On Wed, Jan 02, 2019 at 01:51:01PM +0100, Vlastimil Babka wrote: > > > -> #3 (&base->lock){-.-.}: > > > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 > > > [inline] > > > _raw_spin_lock_irqsave+0x99/0x

Re: possible deadlock in __wake_up_common_lock

2019-01-07 Thread Peter Zijlstra
On Wed, Jan 02, 2019 at 01:51:01PM +0100, Vlastimil Babka wrote: > > -> #3 (&base->lock){-.-.}: > > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 > > [inline] > > _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152 > > lock_timer_base+0xbb/0x2b0 ke

Re: possible deadlock in __wake_up_common_lock

2019-01-03 Thread Mel Gorman
On Thu, Jan 03, 2019 at 02:40:35PM -0500, Qian Cai wrote: > > Signed-off-by: Mel Gorman > > Tested-by: Qian Cai Thanks! -- Mel Gorman SUSE Labs

Re: possible deadlock in __wake_up_common_lock

2019-01-03 Thread Qian Cai
On 1/3/19 11:37 AM, Mel Gorman wrote: > On Wed, Jan 02, 2019 at 07:29:43PM +0100, Dmitry Vyukov wrote: This wakeup_kswapd is new due to Mel's 1c30844d2dfe ("mm: reclaim small amounts of memory when an external fragmentation event occurs") so CC Mel. >>> >>> New year new bugs :( >> >>

Re: possible deadlock in __wake_up_common_lock

2019-01-03 Thread Mel Gorman
On Wed, Jan 02, 2019 at 07:29:43PM +0100, Dmitry Vyukov wrote: > > > This wakeup_kswapd is new due to Mel's 1c30844d2dfe ("mm: reclaim small > > > amounts of memory when an external fragmentation event occurs") so CC Mel. > > > > > > > New year new bugs :( > > Old too :( > https://syzkaller.appspo

Re: possible deadlock in __wake_up_common_lock

2019-01-02 Thread Qian Cai
On 1/2/19 8:28 PM, Tetsuo Handa wrote: > On 2019/01/03 3:19, Qian Cai wrote: >> On 1/2/19 1:06 PM, Mel Gorman wrote: >> >>> While I recognise there is no test case available, how often does this >>> trigger in syzbot as it would be nice to have some confirmation any >>> patch is really fixing the p

Re: possible deadlock in __wake_up_common_lock

2019-01-02 Thread Tetsuo Handa
On 2019/01/03 3:19, Qian Cai wrote: > On 1/2/19 1:06 PM, Mel Gorman wrote: > >> While I recognise there is no test case available, how often does this >> trigger in syzbot as it would be nice to have some confirmation any >> patch is really fixing the problem. > > I think I did manage to trigger

Re: possible deadlock in __wake_up_common_lock

2019-01-02 Thread Dmitry Vyukov
On Wed, Jan 2, 2019 at 7:06 PM Mel Gorman wrote: > > On Wed, Jan 02, 2019 at 01:51:01PM +0100, Vlastimil Babka wrote: > > On 1/2/19 9:51 AM, syzbot wrote: > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit:f346b0becb1b Merge branch 'akpm' (patches from Andrew

Re: possible deadlock in __wake_up_common_lock

2019-01-02 Thread Qian Cai
On 1/2/19 1:06 PM, Mel Gorman wrote: > While I recognise there is no test case available, how often does this > trigger in syzbot as it would be nice to have some confirmation any > patch is really fixing the problem. I think I did manage to trigger this every time running a mmap() workload causi

Re: possible deadlock in __wake_up_common_lock

2019-01-02 Thread Mel Gorman
On Wed, Jan 02, 2019 at 01:51:01PM +0100, Vlastimil Babka wrote: > On 1/2/19 9:51 AM, syzbot wrote: > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit:f346b0becb1b Merge branch 'akpm' (patches from Andrew) > > git tree: upstream > > console output: https://syzka

Re: possible deadlock in __wake_up_common_lock

2019-01-02 Thread Vlastimil Babka
On 1/2/19 9:51 AM, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit:f346b0becb1b Merge branch 'akpm' (patches from Andrew) > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1510cefd40 > kernel config: https://syzkaller.a

possible deadlock in __wake_up_common_lock

2019-01-02 Thread syzbot
Hello, syzbot found the following crash on: HEAD commit:f346b0becb1b Merge branch 'akpm' (patches from Andrew) git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1510cefd40 kernel config: https://syzkaller.appspot.com/x/.config?x=c255c77ba370fe7c dashboar