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Commit 6eac3f93f5e6b7256fb20b7608d62ec192da12be

Authored by Vasily Averin
Committed by Linus Torvalds
1 parent ebed4bfc8d
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

[PATCH] missing unused dentry in prune_dcache()? 

On the the following patch:
http://linux.bkbits.net:8080/linux-2.6/gnupatch@449b144ecSF1rYskg3q-SeR2vf88zg

# ChangeSet
#   2006/06/22 15:05:57-07:00 neilb@suse.de
#   [PATCH] Fix dcache race during umount

#   If prune_dcache finds a dentry that it cannot free, it leaves it where it
#   is (at the tail of the list) and exits, on the assumption that some other
#   thread will be removing that dentry soon.

However as far as I see this comment is not correct: when we cannot take
s_umount rw_semaphore (for example because it was taken in do_remount) this
dentry is already extracted from dentry_unused list and we do not add it
into the list again.  Therefore dentry will not be found by prune_dcache()
and shrink_dcache_sb() and will leave in memory very long time until the
partition will be unmounted.

The patch adds this dentry into tail of the dentry_unused list.

Signed-off-by: Vasily Averin <vvs@sw.ru>
Cc: Neil Brown <neilb@suse.de>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Showing 1 changed file with 5 additions and 4 deletions Side-by-side Diff

... ... @@ -478,11 +478,12 @@
478 478 up_read(s_umount);
479 479 }
480 480 spin_unlock(&dentry->d_lock);
481   - /* Cannot remove the first dentry, and it isn't appropriate
482   - * to move it to the head of the list, so give up, and try
483   - * later
  481 + /*
  482 + * Insert dentry at the head of the list as inserting at the
  483 + * tail leads to a cycle.
484 484 */
485   - break;
  485 + list_add(&dentry->d_lru, &dentry_unused);
  486 + dentry_stat.nr_unused++;
486 487 }
487 488 spin_unlock(&dcache_lock);
488 489 }