From b584c45b6066fd9799c44ffb9badcb5db351c8a6 Mon Sep 17 00:00:00 2001 From: Cen Zhang Date: Tue, 20 Oct 2026 11:45:04 +0800 Subject: [PATCH] ocfs2: drain quorum work before removing the cluster The configured cluster must remain available until an in-flight quorum decision has finished using its fencing method. o2quo_make_decision() drops qs_lock before calling o2quo_fence_self(), which marks heartbeat regions for unclean stop and then reads o2nm_single_cluster->cl_fence_method. Cluster removal clears the singleton without waiting for this independent system-workqueue item. When a failed-quorum decision overlaps removal of the heartbeat regions, nodes and cluster through configfs, the worker can be preempted after marking the regions and resume after the singleton has been cleared: Quorum worker Configfs removal select fence; drop qs_lock o2hb_stop_all_regions() remove regions; join heartbeat threads remove nodes; stop o2net clear singleton; release cluster read cl_fence_method The resumed read dereferences NULL instead of applying the configured fencing method. The heartbeat thread's dependency protects the local node only until the thread exits, and draining o2net does not wait for qs_work. Add o2quo_flush_work() to drain pending or running quorum decisions before clearing the singleton in o2nm_cluster_group_drop_item(). By this point the heartbeat regions and nodes have been removed, so their work publishers are stopped. The worker can finish while the cluster and its configured fencing method remain available. It does not acquire the configfs mutex held by the removal path. Keep o2quo_exit() as the counterpart of o2quo_init() for module teardown and initialization failure, and have it call the same drain helper. Cluster removal uses only the explicitly named drain operation. KASAN report as below: Oops: general protection fault, probably for non-canonical address 0xdffffc000000011b: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x00000000000008d8-0x00000000000008df] CPU: 0 UID: 0 PID: 72 Comm: kworker/0:2 Not tainted 7.3.0-rc4-next-20260921-pmb-ocfs2-functional-v1+ #1 PREEMPT(lazy) Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: events o2quo_make_decision RIP: 0010:o2quo_fence_self+0x65/0x200 Register dump omitted. Call Trace: o2quo_make_decision+0x345/0x3a0 ? __pfx_o2quo_make_decision+0x10/0x10 ? process_one_work+0x834/0x1b40 ? srso_alias_return_thunk+0x5/0xfbef5 ? lock_release+0xc8/0x290 ? srso_alias_return_thunk+0x5/0xfbef5 process_one_work+0x9a8/0x1b40 ? __pfx_process_one_work+0x10/0x10 ? lock_acquire+0x190/0x300 ? lock_is_held_type+0x8f/0x100 ? srso_alias_return_thunk+0x5/0xfbef5 worker_thread+0x65c/0xe40 ? srso_alias_return_thunk+0x5/0xfbef5 ? __kthread_parkme+0x177/0x220 ? srso_alias_return_thunk+0x5/0xfbef5 ? __pfx_worker_thread+0x10/0x10 kthread+0x351/0x460 ? srso_alias_return_thunk+0x5/0xfbef5 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x659/0x940 ? __pfx_ret_from_fork+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? __switch_to+0x74f/0xf70 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 Modules linked in: ---[ end trace 0000000000000000 ]--- Link: https://lore.kernel.org/pm-ocfs2-objects-candidate-0064-v5-e3870bf6571b80b07b52@gmail.com Fixes: f6656d26d17b ("ocfs2/cluster: Make fence method configurable - v2") Signed-off-by: Cen Zhang Signed-off-by: Andrew Morton Reviewed-by: Joseph Qi Assisted-by: LLM Cc: Mark Fasheh Cc: Joel Becker Cc: Heming Zhao Cc: Jia-Ju Bai Cc: Cc: --- fs/ocfs2/cluster/nodemanager.c | 3 +++ fs/ocfs2/cluster/quorum.c | 7 ++++++- fs/ocfs2/cluster/quorum.h | 1 + 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/fs/ocfs2/cluster/nodemanager.c b/fs/ocfs2/cluster/nodemanager.c index e08850a5d736..ced4fe6d3b59 100644 --- a/fs/ocfs2/cluster/nodemanager.c +++ b/fs/ocfs2/cluster/nodemanager.c @@ -12,6 +12,7 @@ #include "tcp.h" #include "nodemanager.h" #include "heartbeat.h" +#include "quorum.h" #include "masklog.h" #include "sys.h" @@ -740,6 +741,8 @@ static void o2nm_cluster_group_drop_item(struct config_group *group, struct conf struct o2nm_cluster *cluster = to_o2nm_cluster(item); BUG_ON(o2nm_single_cluster != cluster); + /* Drain quorum work before it loses access to the cluster. */ + o2quo_flush_work(); o2nm_single_cluster = NULL; configfs_remove_default_groups(&cluster->cl_group); diff --git a/fs/ocfs2/cluster/quorum.c b/fs/ocfs2/cluster/quorum.c index bfb8b456876c..ab5b3d4fd0e8 100644 --- a/fs/ocfs2/cluster/quorum.c +++ b/fs/ocfs2/cluster/quorum.c @@ -318,9 +318,14 @@ void o2quo_init(void) INIT_WORK(&qs->qs_work, o2quo_make_decision); } -void o2quo_exit(void) +void o2quo_flush_work(void) { struct o2quo_state *qs = &o2quo_state; flush_work(&qs->qs_work); } + +void o2quo_exit(void) +{ + o2quo_flush_work(); +} diff --git a/fs/ocfs2/cluster/quorum.h b/fs/ocfs2/cluster/quorum.h index d64bf4482a4a..1ce5fc2a8ca9 100644 --- a/fs/ocfs2/cluster/quorum.h +++ b/fs/ocfs2/cluster/quorum.h @@ -8,6 +8,7 @@ void o2quo_init(void); void o2quo_exit(void); +void o2quo_flush_work(void); void o2quo_hb_up(u8 node); void o2quo_hb_down(u8 node);