From: Hugh Dickins Date: Sat, 14 May 2011 19:06:42 +0000 (-0700) Subject: tmpfs: fix race between swapoff and writepage X-Git-Tag: v2.6.39~24 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=05bf86b4ccfd0f197da61c67bd372111d15a6620;p=pandora-kernel.git tmpfs: fix race between swapoff and writepage Shame on me! Commit b1dea800ac39 "tmpfs: fix race between umount and writepage" fixed the advertized race, but introduced another: as even its comment makes clear, we cannot safely rely on a peek at list_empty() while holding no lock - until info->swapped is set, shmem_unuse_inode() may delete any formerly-swapped inode from the shmem_swaplist, which in this case would leave a swap area impossible to swapoff. Although I don't relish taking the mutex every time, I don't care much for the alternatives either; and at least the peek at list_empty() in shmem_evict_inode() (a hotter path since most inodes would never have been swapped) remains safe, because we already truncated the whole file. Signed-off-by: Hugh Dickins Cc: stable@kernel.org Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed