Messages in this thread Patch in this message | | | From | Shuah Khan <> | Subject | [PATCH v2] workqueue: Don't record workqueue stack holding raw_spin_lock | Date | Thu, 2 Sep 2021 14:01:34 -0600 |
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When CONFIG_PROVE_RAW_LOCK_NESTING=y and CONFIG_KASAN are enabled, kasan_record_aux_stack() runs into "BUG: Invalid wait context" when it tries to allocate memory attempting to acquire spinlock in page allocation code while holding workqueue pool raw_spinlock.
There are several instances of this problem when block layer tries to __queue_work(). Call trace from one of these instances is below:
kblockd_mod_delayed_work_on() mod_delayed_work_on() __queue_delayed_work() __queue_work() (rcu_read_lock, raw_spin_lock pool->lock held) insert_work() kasan_record_aux_stack() kasan_save_stack() stack_depot_save() alloc_pages() __alloc_pages() get_page_from_freelist() rm_queue() rm_queue_pcplist() local_lock_irqsave(&pagesets.lock, flags); [ BUG: Invalid wait context triggered ]
Fix it by calling kasan_record_aux_stack() conditionally only when CONFIG_PROVE_RAW_LOCK_NESTING is not enabled. After exploring other options such as calling kasan_record_aux_stack() after releasing the pool lock, opting for a least disruptive path of stubbing this record function to avoid nesting raw spinlock and spinlock.
============================= [ BUG: Invalid wait context ] 5.14.0-rc7+ #8 Not tainted ----------------------------- snap/532 is trying to lock: ffff888374f32ba0 (lock#2){..-.}-{3:3}, at: get_page_from_freelist (mm/page_alloc.c:3665 mm/page_alloc.c:3703 mm/page_alloc.c:4165) other info that might help us debug this: context-{5:5} 3 locks held by snap/532: #0: ffff888139fa4408 (&type->i_mutex_dir_key#10){.+.+}-{4:4}, at: walk_component (fs/namei.c:1663 fs/namei.c:1959) #1: ffffffffab870c40 (rcu_read_lock){....}-{1:3}, at: __queue_work (./arch/x86/include/asm/preempt.h:80 ./include/linux/rcupdate.h:68 ./include/linux/rcupdate.h:685 kernel/workqueue.c:1421) #2: ffff888374f36cd8 (&pool->lock){-.-.}-{2:2}, at: __queue_work (kernel/workqueue.c:1466) stack backtrace: CPU: 14 PID: 532 Comm: snap Not tainted 5.14.0-rc7+ #8 Hardware name: LENOVO 90Q30008US/3728, BIOS O4ZKT1CA 09/16/2020 Call Trace: dump_stack_lvl (lib/dump_stack.c:106 (discriminator 4)) dump_stack (lib/dump_stack.c:113) __lock_acquire.cold (kernel/locking/lockdep.c:4666 kernel/locking/lockdep.c:4727 kernel/locking/lockdep.c:4965) ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4873) ? lock_is_held_type (kernel/locking/lockdep.c:5368 kernel/locking/lockdep.c:5668) lock_acquire (kernel/locking/lockdep.c:438 kernel/locking/lockdep.c:5627 kernel/locking/lockdep.c:5590) ? get_page_from_freelist (mm/page_alloc.c:3665 mm/page_alloc.c:3703 mm/page_alloc.c:4165) ? lock_release (kernel/locking/lockdep.c:5593) ? __kasan_check_read (mm/kasan/shadow.c:32) ? __lock_acquire (kernel/locking/lockdep.c:5019) ? __zone_watermark_ok (./include/linux/list.h:282 ./include/linux/mmzone.h:111 mm/page_alloc.c:3908) get_page_from_freelist (./include/linux/local_lock_internal.h:43 mm/page_alloc.c:3665 mm/page_alloc.c:3703 mm/page_alloc.c:4165) ? get_page_from_freelist (mm/page_alloc.c:3665 mm/page_alloc.c:3703 mm/page_alloc.c:4165) ? lock_is_held_type (kernel/locking/lockdep.c:5368 kernel/locking/lockdep.c:5668) ? is_bpf_text_address (./arch/x86/include/asm/preempt.h:85 ./include/linux/rcupdate.h:73 ./include/linux/rcupdate.h:719 kernel/bpf/core.c:708) ? lock_downgrade (kernel/locking/lockdep.c:5633) ? __zone_watermark_ok (mm/page_alloc.c:4054) __alloc_pages (mm/page_alloc.c:5391) ? __alloc_pages_slowpath.constprop.0 (mm/page_alloc.c:5354) ? create_prof_cpu_mask (kernel/stacktrace.c:82) ? _find_first_bit (lib/find_bit.c:83) alloc_pages (mm/mempolicy.c:2249) stack_depot_save (lib/stackdepot.c:304) ? lock_is_held_type (kernel/locking/lockdep.c:5368 kernel/locking/lockdep.c:5668) kasan_save_stack (mm/kasan/common.c:41) ? kasan_save_stack (mm/kasan/common.c:39) ? kasan_record_aux_stack (mm/kasan/generic.c:348) ? insert_work (./include/linux/instrumented.h:71 ./include/asm-generic/bitops/instrumented-non-atomic.h:134 kernel/workqueue.c:616 kernel/workqueue.c:623 kernel/workqueue.c:1335) ? __queue_work (kernel/workqueue.c:1501) ? __queue_delayed_work (kernel/workqueue.c:1657) ? mod_delayed_work_on (kernel/workqueue.c:1720) ? kblockd_mod_delayed_work_on (block/blk-core.c:1633) ? __blk_mq_delay_run_hw_queue (block/blk-mq.c:1567) ? blk_mq_run_hw_queue (block/blk-mq.c:1610) ? blk_mq_sched_insert_request (block/blk-mq-sched.c:480) ? blk_mq_submit_bio (block/blk-mq.c:2276)
Fixes: e89a85d63fb2 ("workqueue: kasan: record workqueue stack") Signed-off-by: Shuah Khan <skhan@linuxfoundation.org> --- Changes since v1: -- Instead of changing when record happens, disable record when CONFIG_PROVE_RAW_LOCK_NESTING=y kernel/workqueue.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index f148eacda55a..435970ef81ae 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1328,8 +1328,16 @@ static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, { struct worker_pool *pool = pwq->pool; - /* record the work call stack in order to print it in KASAN reports */ + /* + * record the work call stack in order to print it in KASAN reports + * Doing this when CONFIG_PROVE_RAW_LOCK_NESTING is enabled results + * in nesting raw spinlock with page allocation spinlock. + * + * Avoid recording when CONFIG_PROVE_RAW_LOCK_NESTING is enabled. + */ +#if !defined(CONFIG_PROVE_RAW_LOCK_NESTING) kasan_record_aux_stack(work); +#endif /* we own @work, set data and link */ set_work_pwq(work, pwq, extra_flags); -- 2.30.2
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