Date: Wed, 18 Mar 2009 09:59:14 +0100 From: Attilio Rao <attilio@freebsd.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: Yoshihiro Ota <ota@j.email.ne.jp>, Peter Holm <pho@freebsd.org>, freebsd-fs@freebsd.org Subject: Re: kern/132597: [tmpfs] [panic] tmpfs-related panic while interrupting a port build on tmpfs WRKDIR Message-ID: <3bbf2fe10903180159x10d2c721rf9ff4147a5c75ec7@mail.gmail.com> In-Reply-To: <20090314203215.GA41617@deviant.kiev.zoral.com.ua> References: <200903140450.n2E4o3to011990@freefall.freebsd.org> <20090314102135.GA93077@x2.osted.lan> <20090314203215.GA41617@deviant.kiev.zoral.com.ua>
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2009/3/14, Kostik Belousov <kostikbel@gmail.com>: > On Sat, Mar 14, 2009 at 11:21:35AM +0100, Peter Holm wrote: > > On Sat, Mar 14, 2009 at 04:50:03AM +0000, Yoshihiro Ota wrote: > > > The following reply was made to PR kern/132597; it has been noted by GNATS. > > > > > > From: Yoshihiro Ota <ota@j.email.ne.jp> > > > To: bug-followup@FreeBSD.org > > > Cc: bf2006a@yahoo.com > > > Subject: Re: kern/132597: [tmpfs] [panic] tmpfs-related panic while > > > interrupting a port build on tmpfs WRKDIR > > > Date: Sat, 14 Mar 2009 00:42:58 -0400 > > > > > > Which ports were you compiling when panic happened? > > > > > > Hiro > > > > The panic in this PR looks a lot like the one I reported to attilio@ > > > > http://people.freebsd.org/~pho/stress/log/attilio022.txt > > > > It was just regular FS load that provoked it. > > > It seems to be quite clean what is going on there. In fact, there are > two issues: > > First is the usual problem of DOTDOT lookup that shall be fixed in style > of vn_vget_ino() by busying mp before unlocking dvp. > > Second one is the reason for the panic. The tmpfs vnode is unlocked, and > then corresponding tmpfs _node_ is passed to the tmpfs_alloc_vp(). > Since the vnode may be reclaimed after the unlock, passed node might > become freed. Then, the tmpfs_alloc_vp() would operate on the freed > memory. So I have a question. In the tmpfs_lookup() there is dvp with gets vhold() before to unlock the dvp vnode lock. That should not be enough to prevent recycling and freeing of the structure? Thanks, Attilio -- Peace can only be achieved by understanding - A. Einstein
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