From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, xfs@oss.sgi.com
Subject: Re: [PATCH 08/12] superblock: introduce per-sb cache shrinker infrastructure
Date: Sat, 4 Jun 2011 01:42:31 +0100 [thread overview]
Message-ID: <20110604004231.GV11521@ZenIV.linux.org.uk> (raw)
In-Reply-To: <1306998067-27659-9-git-send-email-david@fromorbit.com>
> @@ -278,7 +325,12 @@ void generic_shutdown_super(struct super_block *sb)
> {
> const struct super_operations *sop = sb->s_op;
>
> -
> + /*
> + * shut down the shrinker first so we know that there are no possible
> + * races when shrinking the dcache or icache. Removes the need for
> + * external locking to prevent such races.
> + */
> + unregister_shrinker(&sb->s_shrink);
> if (sb->s_root) {
> shrink_dcache_for_umount(sb);
> sync_filesystem(sb);
What it means is that shrinker_rwsem now nests inside ->s_umount... IOW,
if any ->shrink() gets stuck, so does every generic_shutdown_super().
I'm still not convinced it's a good idea - especially since _this_
superblock will be skipped anyway. Is there any good reason to evict
shrinker that early? Note that doing that after ->s_umount is dropped
should be reasonably safe - your shrinker will see that superblock is
doomed if it's called anywhere in that window...
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WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, xfs@oss.sgi.com
Subject: Re: [PATCH 08/12] superblock: introduce per-sb cache shrinker infrastructure
Date: Sat, 4 Jun 2011 01:42:31 +0100 [thread overview]
Message-ID: <20110604004231.GV11521@ZenIV.linux.org.uk> (raw)
In-Reply-To: <1306998067-27659-9-git-send-email-david@fromorbit.com>
> @@ -278,7 +325,12 @@ void generic_shutdown_super(struct super_block *sb)
> {
> const struct super_operations *sop = sb->s_op;
>
> -
> + /*
> + * shut down the shrinker first so we know that there are no possible
> + * races when shrinking the dcache or icache. Removes the need for
> + * external locking to prevent such races.
> + */
> + unregister_shrinker(&sb->s_shrink);
> if (sb->s_root) {
> shrink_dcache_for_umount(sb);
> sync_filesystem(sb);
What it means is that shrinker_rwsem now nests inside ->s_umount... IOW,
if any ->shrink() gets stuck, so does every generic_shutdown_super().
I'm still not convinced it's a good idea - especially since _this_
superblock will be skipped anyway. Is there any good reason to evict
shrinker that early? Note that doing that after ->s_umount is dropped
should be reasonably safe - your shrinker will see that superblock is
doomed if it's called anywhere in that window...
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, xfs@oss.sgi.com
Subject: Re: [PATCH 08/12] superblock: introduce per-sb cache shrinker infrastructure
Date: Sat, 4 Jun 2011 01:42:31 +0100 [thread overview]
Message-ID: <20110604004231.GV11521@ZenIV.linux.org.uk> (raw)
In-Reply-To: <1306998067-27659-9-git-send-email-david@fromorbit.com>
> @@ -278,7 +325,12 @@ void generic_shutdown_super(struct super_block *sb)
> {
> const struct super_operations *sop = sb->s_op;
>
> -
> + /*
> + * shut down the shrinker first so we know that there are no possible
> + * races when shrinking the dcache or icache. Removes the need for
> + * external locking to prevent such races.
> + */
> + unregister_shrinker(&sb->s_shrink);
> if (sb->s_root) {
> shrink_dcache_for_umount(sb);
> sync_filesystem(sb);
What it means is that shrinker_rwsem now nests inside ->s_umount... IOW,
if any ->shrink() gets stuck, so does every generic_shutdown_super().
I'm still not convinced it's a good idea - especially since _this_
superblock will be skipped anyway. Is there any good reason to evict
shrinker that early? Note that doing that after ->s_umount is dropped
should be reasonably safe - your shrinker will see that superblock is
doomed if it's called anywhere in that window...
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next prev parent reply other threads:[~2011-06-04 0:42 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-02 7:00 [PATCH 0/12] Per superblock cache reclaim Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-02 7:00 ` [PATCH 01/12] vmscan: add shrink_slab tracepoints Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-20 0:44 ` KOSAKI Motohiro
2011-06-20 0:44 ` KOSAKI Motohiro
2011-06-20 0:44 ` KOSAKI Motohiro
2011-06-20 0:44 ` KOSAKI Motohiro
2011-06-20 0:53 ` Dave Chinner
2011-06-20 0:53 ` Dave Chinner
2011-06-20 0:53 ` Dave Chinner
2011-06-20 0:53 ` Dave Chinner
2011-06-02 7:00 ` [PATCH 02/12] vmscan: shrinker->nr updates race and go wrong Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-20 0:46 ` KOSAKI Motohiro
2011-06-20 0:46 ` KOSAKI Motohiro
2011-06-20 0:46 ` KOSAKI Motohiro
2011-06-20 1:25 ` Dave Chinner
2011-06-20 1:25 ` Dave Chinner
2011-06-20 1:25 ` Dave Chinner
2011-06-20 4:30 ` KOSAKI Motohiro
2011-06-20 4:30 ` KOSAKI Motohiro
2011-06-20 4:30 ` KOSAKI Motohiro
2011-06-02 7:00 ` [PATCH 03/12] vmscan: reduce wind up shrinker->nr when shrinker can't do work Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-20 0:51 ` KOSAKI Motohiro
2011-06-20 0:51 ` KOSAKI Motohiro
2011-06-20 0:51 ` KOSAKI Motohiro
2011-06-20 0:51 ` KOSAKI Motohiro
2011-06-21 5:09 ` Dave Chinner
2011-06-21 5:09 ` Dave Chinner
2011-06-21 5:09 ` Dave Chinner
2011-06-21 5:09 ` Dave Chinner
2011-06-21 5:27 ` KOSAKI Motohiro
2011-06-21 5:27 ` KOSAKI Motohiro
2011-06-21 5:27 ` KOSAKI Motohiro
2011-06-02 7:00 ` [PATCH 04/12] vmscan: add customisable shrinker batch size Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-02 7:00 ` Dave Chinner
2011-06-02 7:01 ` [PATCH 05/12] inode: convert inode_stat.nr_unused to per-cpu counters Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` [PATCH 06/12] inode: Make unused inode LRU per superblock Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-04 0:25 ` Al Viro
2011-06-04 0:25 ` Al Viro
2011-06-04 0:25 ` Al Viro
2011-06-04 1:40 ` Dave Chinner
2011-06-04 1:40 ` Dave Chinner
2011-06-04 1:40 ` Dave Chinner
2011-06-02 7:01 ` [PATCH 07/12] inode: move to per-sb LRU locks Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` [PATCH 08/12] superblock: introduce per-sb cache shrinker infrastructure Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-04 0:42 ` Al Viro [this message]
2011-06-04 0:42 ` Al Viro
2011-06-04 0:42 ` Al Viro
2011-06-04 1:52 ` Dave Chinner
2011-06-04 1:52 ` Dave Chinner
2011-06-04 1:52 ` Dave Chinner
2011-06-04 14:08 ` Christoph Hellwig
2011-06-04 14:08 ` Christoph Hellwig
2011-06-04 14:08 ` Christoph Hellwig
2011-06-04 14:19 ` Al Viro
2011-06-04 14:19 ` Al Viro
2011-06-04 14:19 ` Al Viro
2011-06-04 14:24 ` Al Viro
2011-06-04 14:24 ` Al Viro
2011-06-04 14:24 ` Al Viro
2011-06-02 7:01 ` [PATCH 09/12] inode: remove iprune_sem Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` [PATCH 10/12] superblock: add filesystem shrinker operations Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` [PATCH 11/12] vfs: increase shrinker batch size Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 9:30 ` Nicolas Kaiser
2011-06-02 9:30 ` Nicolas Kaiser
2011-06-02 9:30 ` Nicolas Kaiser
2011-06-02 7:01 ` [PATCH 12/12] xfs: make use of new shrinker callout for the inode cache Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-02 7:01 ` Dave Chinner
2011-06-16 11:33 ` [PATCH 0/12] Per superblock cache reclaim Christoph Hellwig
2011-06-16 11:33 ` Christoph Hellwig
2011-06-16 11:33 ` Christoph Hellwig
2011-06-17 3:35 ` KOSAKI Motohiro
2011-06-17 3:35 ` KOSAKI Motohiro
2011-06-17 3:35 ` KOSAKI Motohiro
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