Subject: [merged] ocfs2-dlm-fix-possible-convertion-deadlock.patch removed from -mm tree To: xuejiufei@xxxxxxxxxx,jlbec@xxxxxxxxxxxx,mfasheh@xxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Thu, 05 Jun 2014 12:42:46 -0700 The patch titled Subject: ocfs2/dlm: fix possible convert=sion deadlock has been removed from the -mm tree. Its filename was ocfs2-dlm-fix-possible-convertion-deadlock.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Xue jiufei <xuejiufei@xxxxxxxxxx> Subject: ocfs2/dlm: fix possible convert=sion deadlock We found there is a conversion deadlock when the owner of lockres happened to crash before send DLM_PROXY_AST_MSG for a downconverting lock. The situation is as follows: Node1 Node2 Node3 the owner of lockresA lock_1 granted at EX mode and call ocfs2_cluster_unlock to decrease ex_holders. converting lock_3 from NL to EX send DLM_PROXY_AST_MSG to Node1, asking Node 1 to downconvert. receiving DLM_PROXY_AST_MSG, thread ocfs2dc send DLM_CONVERT_LOCK_MSG to Node2 to downconvert lock_1(EX->NL). lock_1 can be granted and put it into pending_asts list, return DLM_NORMAL. then something happened and Node2 crashed. received DLM_NORMAL, waiting for DLM_PROXY_AST_MSG. selected as the recovery master, receving migrate lock from Node1, queue lock_1 to the tail of converting list. After dlm recovery, converting list in the master of lockresA(Node3) will be: converting list head <-> lock_3(NL->EX) <->lock_1(EX<->NL). Requested mode of lock_3 is not compatible with the granted mode of lock_1, so it can not be granted. and lock_1 can not downconvert because covnerting queue is strictly FIFO. So a deadlock is created. We think function dlm_process_recovery_data() should queue_ast for lock_1 or alter the order of lock_1 and lock_3, so dlm_thread can process lock_1 first. And if there are multiple downconverting locks, they must convert form PR to NL, so no need to sort them. Signed-off-by: joyce.xue <xuejiufei@xxxxxxxxxx> Cc: Mark Fasheh <mfasheh@xxxxxxxx> Cc: Joel Becker <jlbec@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/ocfs2/dlm/dlmrecovery.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff -puN fs/ocfs2/dlm/dlmrecovery.c~ocfs2-dlm-fix-possible-convertion-deadlock fs/ocfs2/dlm/dlmrecovery.c --- a/fs/ocfs2/dlm/dlmrecovery.c~ocfs2-dlm-fix-possible-convertion-deadlock +++ a/fs/ocfs2/dlm/dlmrecovery.c @@ -1986,7 +1986,15 @@ skip_lvb: } if (!bad) { dlm_lock_get(newlock); - list_add_tail(&newlock->list, queue); + if (mres->flags & DLM_MRES_RECOVERY && + ml->list == DLM_CONVERTING_LIST && + newlock->ml.type > + newlock->ml.convert_type) { + /* newlock is doing downconvert, add it to the + * head of converting list */ + list_add(&newlock->list, queue); + } else + list_add_tail(&newlock->list, queue); mlog(0, "%s:%.*s: added lock for node %u, " "setting refmap bit\n", dlm->name, res->lockname.len, res->lockname.name, ml->node); _ Patches currently in -mm which might be from xuejiufei@xxxxxxxxxx are origin.patch ocfs2-revert-the-patch-fix-null-pointer-dereference-when-dismount-and-ocfs2rec-simultaneously.patch ocfs2-dlm-do-not-purge-lockres-that-is-queued-for-assert-master.patch ocfs2-do-not-return-dlm_migrate_response_mastery_ref-to-avoid-endlessloop-during-umount.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html