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Message-ID: <lsq.1444349547.79106754@decadent.org.uk> Date: Fri, 09 Oct 2015 01:12:27 +0100 From: Ben Hutchings <ben@...adent.org.uk> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org CC: akpm@...ux-foundation.org, "Joseph Qi" <joseph.qi@...wei.com>, "Linus Torvalds" <torvalds@...ux-foundation.org>, "Joel Becker" <jlbec@...lplan.org>, "Mark Fasheh" <mfasheh@...e.com> Subject: [PATCH 3.2 015/107] ocfs2: fix BUG in ocfs2_downconvert_thread_do_work() 3.2.72-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Joseph Qi <joseph.qi@...wei.com> commit 209f7512d007980fd111a74a064d70a3656079cf upstream. The "BUG_ON(list_empty(&osb->blocked_lock_list))" in ocfs2_downconvert_thread_do_work can be triggered in the following case: ocfs2dc has firstly saved osb->blocked_lock_count to local varibale processed, and then processes the dentry lockres. During the dentry put, it calls iput and then deletes rw, inode and open lockres from blocked list in ocfs2_mark_lockres_freeing. And this causes the variable `processed' to not reflect the number of blocked lockres to be processed, which triggers the BUG. Signed-off-by: Joseph Qi <joseph.qi@...wei.com> Cc: Mark Fasheh <mfasheh@...e.com> Cc: Joel Becker <jlbec@...lplan.org> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org> Signed-off-by: Ben Hutchings <ben@...adent.org.uk> --- fs/ocfs2/dlmglue.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/fs/ocfs2/dlmglue.c +++ b/fs/ocfs2/dlmglue.c @@ -3968,9 +3968,13 @@ static void ocfs2_downconvert_thread_do_ osb->dc_work_sequence = osb->dc_wake_sequence; processed = osb->blocked_lock_count; - while (processed) { - BUG_ON(list_empty(&osb->blocked_lock_list)); - + /* + * blocked lock processing in this loop might call iput which can + * remove items off osb->blocked_lock_list. Downconvert up to + * 'processed' number of locks, but stop short if we had some + * removed in ocfs2_mark_lockres_freeing when downconverting. + */ + while (processed && !list_empty(&osb->blocked_lock_list)) { lockres = list_entry(osb->blocked_lock_list.next, struct ocfs2_lock_res, l_blocked_list); list_del_init(&lockres->l_blocked_list); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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