Messages in this thread | | | Date | Wed, 30 Apr 2014 20:42:01 +0200 | Subject | Re: dcache shrink list corruption? | From | Miklos Szeredi <> |
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On Wed, Apr 30, 2014 at 8:36 PM, Al Viro <viro@zeniv.linux.org.uk> wrote: > 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@zeniv.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?
Message-ID: <20140430154958.GC3113@tucsk.piliscsaba.szeredi.hu>
> > 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...
Exactly.
Thanks, Miklos
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