Date: Wed, 27 May 2009 14:22:29 -0400
From: John Baldwin <jhb@freebsd.org>
To: freebsd-current@freebsd.org
Cc: Artem Belevich <fbsdlist@src.cx>
Subject: Re: ZFS : panic("sleeping thread")
Message-ID: <200905271422.30177.jhb@freebsd.org>
In-Reply-To: <ed91d4a80905271058mbc1fc68g184def5097080cbc@mail.gmail.com>
References: <ed91d4a80905271058mbc1fc68g184def5097080cbc@mail.gmail.com>
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On Wednesday 27 May 2009 1:58:49 pm Artem Belevich wrote: > Hi, > > While recent ZFS improvements got rid of random hangs I used to see, > there's still one problem that I keep running into -- panic in ZFS > under heavy load. I can reproduce it by doing a build with -j16 in a > jail running i386 binaries on -CURRENT/amd64 running on a box with > quad-core CPU. It takes a while to reproduce, but it usually shows up > within couple of hours. > > Sleeping thread (tid 100606, pid 32147) owns a non-sleepable lock > sched_switch() at sched_switch+0xed > mi_switch() at mi_switch+0x16f > sleepq_wait() at sleepq_wait+0x42 > _sx_xlock_hard() at _sx_xlock_hard+0x1f0 > _sx_xlock() at _sx_xlock+0x4e > rrw_exit() at rrw_exit+0x1d > zfs_freebsd_getattr() at zfs_freebsd_getattr+0x2be > VOP_GETATTR_APV() at VOP_GETATTR_APV+0x44 > filt_vfsread() at filt_vfsread+0x51 > knote() at knote+0xc2 > VOP_WRITE_APV() at VOP_WRITE_APV+0x11f > vn_write() at vn_write+0x279 > dofilewrite() at dofilewrite+0x85 > kern_writev() at kern_writev+0x60 > write() at write+0x54 > ia32_syscall() at ia32_syscall+0x236 > Xint0x80_syscall() at Xint0x80_syscall+0x85 > --- syscall (4, FreeBSD ELF32, write), rip = 0x78162153, rsp = > 0xffff945c, rbp = 0xffff9478 --- > > It appears that locking within ZFS conflicts with vnode locking. The > back-trace is always the same. I think it is the knote locking that is actually the problem. knote() is acquiring the KQ_LOCK and I think this lock needs to be dropped while invoking VOP_GETATTR(). -- John Baldwin
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