Date: Wed, 19 Aug 1998 11:04:33 -0400 (EDT) From: Luoqi Chen <luoqi@watermarkgroup.com> To: regnauld@deepo.prosa.dk, sos@FreeBSD.ORG Cc: croot@btp1da.phy.uni-bayreuth.de, current@FreeBSD.ORG, smp@FreeBSD.ORG Subject: Re: softupdates and smp crash Message-ID: <199808191504.LAA05903@lor.watermarkgroup.com>
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> In reply to Philippe Regnauld who wrote: > > #0 boot (howto=260) at ../../kern/kern_shutdown.c:286 > > #1 0xf01151c1 in panic (fmt=0xf01ab861 "softdep_lock: locking against myself") > > at ../../kern/kern_shutdown.c:429 > > #2 0xf01ab8c9 in acquire_lock (lk=0xf02265ac) > > at ../../ufs/ffs/ffs_softdep.c:263 > > +-> #3 0xf01aee54 in initiate_write_filepage (pagedep=0xf0c49e00, bp=0xf35300b0) > > | at ../../ufs/ffs/ffs_softdep.c:2745 > > | #4 0xf01aecbf in softdep_disk_io_initiation (bp=0xf35300b0) > > | > > I crashed here. > > > I tried it on my play-smp machine it panics also... > We can still say for sure that softupdates are NOT SMP safe... > > -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > Søren Schmidt (sos@FreeBSD.org) FreeBSD Core Team > Even more code to hack -- will it ever end? > .. > There is a race window between a directory entry is removed and dependency for that directory entry is deallocated. The reason that the race window has manifested itself on SMP is that the syncer process is a kernel thread, so we can have two processes both running in kernel mode. The simplest solution for now, IMO, is to make syncer process honor the giant lock. The long term solution is, of course, close those race windows one by one. -lq To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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