I found this related information at Red Hat EL 4.8's RHSA-2009:0331-14. The trouble caused by race conditions.
Information from Red Hat: * http://rhn.redhat.com/errata/RHSA-2009-0331.html * => https://bugzilla.redhat.com/show_bug.cgi?id=476533 (published info, link from RHSA-2009:0331-14) * => https://bugzilla.redhat.com/show_bug.cgi?id=460179 (this is Red Hat's private) * Red Hat's patchname:linux-2.6.9-fs-fix-it-already-cleared-for-block-errors.patch linux/fs/buffer.c::void unlock_buffer is : { + smp_mb__before_clear_bit(); clear_bit_unlock(BH_Lock, &bh->b_state); smp_mb__after_clear_bit(); wake_up_bit(&bh->b_state, BH_Lock); } They said, > a misplaced memory barrier at unlock_buffer() could lead to a concurrent > h_refcounter update which produced a reference counter leak and, later, a > double free in ext3_xattr_release_block(). Consequent to the double free, > ext3 reported an error > > ext3_free_blocks_sb: bit already cleared for block [block number] > > and mounted itself as read-only. With this update, the memory barrier is > now placed before the buffer head lock bit, forcing the write order and > preventing the double free. (BZ#476533) -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
