Messages in this thread | | | Date | Fri, 10 Mar 2006 22:47:38 +0530 | From | Balbir Singh <> | Subject | Re: [PATCH] Fix shrink_dcache_parent() against shrink_dcache_memory() race (3rd updated patch)] |
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On Fri, Mar 10, 2006 at 01:31:53PM +0100, Jan Blunck wrote: > On Fri, Mar 10, Neil Brown wrote: > > > -static void prune_dcache(int count) > > +static void prune_dcache(int count, struct super_block *sb) > > { > > spin_lock(&dcache_lock); > > for (; count ; count--) { > > @@ -417,8 +425,10 @@ static void prune_dcache(int count) > > spin_unlock(&dentry->d_lock); > > continue; > > } > > - /* If the dentry was recently referenced, don't free it. */ > > - if (dentry->d_flags & DCACHE_REFERENCED) { > > + /* If the dentry was recently referenced, or is for > > + * a unmounting filesystem, don't free it. */ > > + if ((dentry->d_flags & DCACHE_REFERENCED) || > > + (dentry->d_sb != sb && dentry->d_sb->s_root == NULL)) { > > dentry->d_flags &= ~DCACHE_REFERENCED; > > list_add(&dentry->d_lru, &dentry_unused); > > dentry_stat.nr_unused++; > > You have to down_read the rw-semaphore sb->s_umount since sb->s_root is > protected by it :(
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Please do not beat me up for suggesting this. I was wondering if it makes sense to add a PF_SHRINKER flag and set it in shrink_slab(). Use my solution, instead of PF_MEMALLOC check against PF_SHRINKER.
I think PF_SHRINKER might be a good idea, it might help us detect races between the shrinker and other subsystems too - not only dcache.
It might be well worth adding in. If there is sufficient interest I can send create and send out a patch.
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