On Tue, Mar 1, 2016 at 4:01 PM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > On Tue, Mar 1, 2016 at 3:44 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: >> On Tue, 01 Mar 2016 13:33:27 +0100, >> Dmitry Vyukov wrote: >>> >>> Hello, >>> >>> The following program creates an unkillable process: >> ..... >>> The hang stack is: >>> >>> [<ffffffff85309f77>] snd_seq_oss_writeq_sync+0x327/0x790 >>> sound/core/seq/oss/seq_oss_writeq.c:121 >> >> This is >> wait_event_interruptible_timeout(q->sync_sleep, ! q->sync_event_put, HZ); >> >> and this should return zero >> if (signal_pending(current)) >> /* interrupted - return 0 to finish sync */ >> q->sync_event_put = 0; >> if (! q->sync_event_put || q->sync_time >= time) >> return 0; >> return 1; >> >>> [<ffffffff852fa353>] snd_seq_oss_drain_write+0x113/0x160 >> >> ... and this loop should break: >> while (snd_seq_oss_writeq_sync(dp->writeq)) >> ; >> >> So, I see no obvious error in the code, so far. >> >> I'm running your test program now with 8 parallel runs, but I couldn't >> reproduce it. Any other specifics? Hummm.. for me this process hangs every time, even if I just run it once from console. I've now retested in on clean commit fc77dbd34c5c99bce46d40a2491937c3bcbd10af (without KASAN/KCOV and with release gcc) and also got the same hang. I can only think of a different config. I've attached mine, please try with it. Are signals delivered if we are already in process of dying? When I kill -9 this process it does not react, so presumably wait is not unblocked...
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