Author: snb
Date: Thu Jun 25 20:40:13 2009
New Revision: 195003
URL: http://svn.freebsd.org/changeset/base/195003
Log:
Fix a bug reported by pho@ where one can induce a panic by decreasing
vfs.ufs.dirhash_maxmem below the current amount of memory used by dirhash.
When
ufsdirhash_build() is called with the memory in use greater than
dirhash_maxmem,
it attempts to free up memory by calling ufsdirhash_recycle(). If successful
in
freeing enough memory, ufsdirhash_recycle() leaves the dirhash list locked.
But
at this point in ufsdirhash_build(), the list is not explicitly unlocked after
the call(s) to ufsdirhash_recycle(). When we next attempt to lock the dirhash
list, we will get a "panic: _mtx_lock_sleep: recursed on non-recursive mutex
dirhash list".
Tested by: pho
Approved by: dwmalone (mentor)
MFC after: 3 weeks
Modified:
head/sys/ufs/ufs/ufs_dirhash.c
Modified: head/sys/ufs/ufs/ufs_dirhash.c
==============================================================================
--- head/sys/ufs/ufs/ufs_dirhash.c Thu Jun 25 20:35:46 2009
(r195002)
+++ head/sys/ufs/ufs/ufs_dirhash.c Thu Jun 25 20:40:13 2009
(r195003)
@@ -348,9 +348,12 @@ ufsdirhash_build(struct inode *ip)
int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot;
/* Take care of a decreased sysctl value. */
- while (ufs_dirhashmem > ufs_dirhashmaxmem)
+ while (ufs_dirhashmem > ufs_dirhashmaxmem) {
if (ufsdirhash_recycle(0) != 0)
return (-1);
+ /* Recycled enough memory, so unlock the list. */
+ DIRHASHLIST_UNLOCK();
+ }
/* Check if we can/should use dirhash. */
if (ip->i_size < ufs_mindirhashsize || OFSFMT(ip->i_vnode) ||
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