Date: Tue, 9 Jun 2009 10:59:14 -0400 From: John Baldwin <jhb@freebsd.org> To: Yuri Pankov <yuri.pankov@gmail.com> Cc: freebsd-current@freebsd.org, Paul Saab <ps@freebsd.org> Subject: Re: panic: knlist not locked, but should be Message-ID: <200906091059.15278.jhb@freebsd.org> In-Reply-To: <20090609135145.GB1290@darklight.homeunix.org> References: <20090609110540.GA1290@darklight.homeunix.org> <200906090937.37562.jhb@freebsd.org> <20090609135145.GB1290@darklight.homeunix.org>
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On Tuesday 09 June 2009 9:51:45 am Yuri Pankov wrote: > On Tue, Jun 09, 2009 at 09:37:37AM -0400, John Baldwin wrote: > > On Tuesday 09 June 2009 7:05:40 am Yuri Pankov wrote: > > > Hi, > > > > > > I'm getting the following panic when running Firefox+nspluginwrapper > > > (which crashes a lot, but paniced the box only two times, if it's even > > > related). -CURRENT/amd64 20080607. > > > > > > Unread portion of the kernel message buffer: > > > panic: knlist not locked, but should be > > > cpuid = 0 > > > KDB: stack backtrace: > > > db_trace_self_wrapper() at db_trace_self_wrapper+0x2a > > > panic() at panic+0x182 > > > knote() at knote+0xea > > > VOP_WRITE_APV() at VOP_WRITE_APV+0x152 > > > vn_rdwr() at vn_rdwr+0x21d > > > vn_rdwr_inchunks() at vn_rdwr_inchunks+0xc2 > > > elf32_coredump() at elf32_coredump+0x109 > > > sigexit() at sigexit+0x810 > > > postsig() at postsig+0x32f > > > ast() at ast+0x3ac > > > doreti_ast() at doreti_ast+0x1f > > > > Are you using ZFS? > > > > -- > > John Baldwin > > Yes, sorry for not mentioning it. This appears to be an interaction with the recent changes to use shared vnode locks for writes on ZFS. Hmm, I think it may be ok to use a shared vnode lock for kevents on vnodes though. The vnode interlock should be sufficient locking for what little work the kevent filters do. As a quick hack for now the MNT_SHARED_WRITES() stuff could avoid using shared locks 'if (!VN_KNLIST_EMPTY(vp))', but I think the longer term fix is to not use the vnode locks for vnode kevents, but use the interlock instead. -- John Baldwin
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