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Date: Wed, 30 Apr 2014 19:36:50 +0100 From: Al Viro <viro@...IV.linux.org.uk> To: Miklos Szeredi <miklos@...redi.hu> Cc: Linus Torvalds <torvalds@...ux-foundation.org>, Dave Chinner <david@...morbit.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-fsdevel <linux-fsdevel@...r.kernel.org> Subject: Re: dcache shrink list corruption? On Wed, Apr 30, 2014 at 07:33:38PM +0200, Miklos Szeredi wrote: > On Wed, Apr 30, 2014 at 6:03 PM, Al Viro <viro@...iv.linux.org.uk> wrote: > > On Wed, Apr 30, 2014 at 05:49:58PM +0200, Miklos Szeredi wrote: > >> > FWIW, the first two are really straightforward expanding the function > >> > into its only callsite. The last needs more splitup. Not sure if the > >> > following is good enough, but it ought to be at least somewhat cleaner. > >> > Combined change is identical to the original, so it doesn't invalidate > >> > the testing so far... > >> > >> Hmm, patches look okay, but I'm wondering if we really need the morgue list and > >> the waiting. Why not just skip dentries that are presently being handled by > >> dentry_kill()? > > > > Who will be freeing them? If we do that from dentry_kill(), we are back to > > needing them removed from shrink list by something called by dput(). And > > if we do that from shrink_dentry_list(), we'd damn better wait for > > dentry_iput() et.al. to finish. > > We can do it from dput if the shrinker gets there first and from the > shrinker if dput manages to finish before. See the updated patch in > the previous mail. Er? The only patch I see is removal of RCU from shrink_dentry_list(), which is fine, but doesn't do anything of that sort. What was the Message-ID? Let me see if I understand what you are proposing: dentry_kill(dentry, 0) seeing DCACHE_DENTRY_KILLED check DCACHE_MAY_FREE, free it's been set dentry_kill(dentry, 1) seeing that we are on shrinker list leave on the list, do the work on killing, retake ->d_lock, if we are still on shrinker list set DCACHE_MAY_FREE, else free it That would probably work... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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