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| author | Adrian Huang <ahuang12@lenovo.com> | 2020-01-14 01:29:32 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-01-14 03:19:02 +0100 |
| commit | 2fe20210fc5f5e62644678b8f927c49f2c6f42a7 (patch) | |
| tree | 360183206c9de94c8930db2110bb900171c6286a /mm/slab_common.c | |
| parent | mm/page-writeback.c: improve arithmetic divisions (diff) | |
| download | linux-2fe20210fc5f5e62644678b8f927c49f2c6f42a7.tar.xz linux-2fe20210fc5f5e62644678b8f927c49f2c6f42a7.zip | |
mm: memcg/slab: call flush_memcg_workqueue() only if memcg workqueue is valid
When booting with amd_iommu=off, the following WARNING message
appears:
AMD-Vi: AMD IOMMU disabled on kernel command-line
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at kernel/workqueue.c:2772 flush_workqueue+0x42e/0x450
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.5.0-rc3-amd-iommu #6
Hardware name: Lenovo ThinkSystem SR655-2S/7D2WRCZ000, BIOS D8E101L-1.00 12/05/2019
RIP: 0010:flush_workqueue+0x42e/0x450
Code: ff 0f 0b e9 7a fd ff ff 4d 89 ef e9 33 fe ff ff 0f 0b e9 7f fd ff ff 0f 0b e9 bc fd ff ff 0f 0b e9 a8 fd ff ff e8 52 2c fe ff <0f> 0b 31 d2 48 c7 c6 e0 88 c5 95 48 c7 c7 d8 ad f0 95 e8 19 f5 04
Call Trace:
kmem_cache_destroy+0x69/0x260
iommu_go_to_state+0x40c/0x5ab
amd_iommu_prepare+0x16/0x2a
irq_remapping_prepare+0x36/0x5f
enable_IR_x2apic+0x21/0x172
default_setup_apic_routing+0x12/0x6f
apic_intr_mode_init+0x1a1/0x1f1
x86_late_time_init+0x17/0x1c
start_kernel+0x480/0x53f
secondary_startup_64+0xb6/0xc0
---[ end trace 30894107c3749449 ]---
x2apic: IRQ remapping doesn't support X2APIC mode
x2apic disabled
The warning is caused by the calling of 'kmem_cache_destroy()'
in free_iommu_resources(). Here is the call path:
free_iommu_resources
kmem_cache_destroy
flush_memcg_workqueue
flush_workqueue
The root cause is that the IOMMU subsystem runs before the workqueue
subsystem, which the variable 'wq_online' is still 'false'. This leads
to the statement 'if (WARN_ON(!wq_online))' in flush_workqueue() is
'true'.
Since the variable 'memcg_kmem_cache_wq' is not allocated during the
time, it is unnecessary to call flush_memcg_workqueue(). This prevents
the WARNING message triggered by flush_workqueue().
Link: http://lkml.kernel.org/r/20200103085503.1665-1-ahuang12@lenovo.com
Fixes: 92ee383f6daab ("mm: fix race between kmem_cache destroy, create and deactivate")
Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
Reported-by: Xiaochun Lee <lixc17@lenovo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab_common.c')
| -rw-r--r-- | mm/slab_common.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c index f0ab6d4ceb4c..0d95ddea13b0 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -903,7 +903,8 @@ static void flush_memcg_workqueue(struct kmem_cache *s) * deactivates the memcg kmem_caches through workqueue. Make sure all * previous workitems on workqueue are processed. */ - flush_workqueue(memcg_kmem_cache_wq); + if (likely(memcg_kmem_cache_wq)) + flush_workqueue(memcg_kmem_cache_wq); /* * If we're racing with children kmem_cache deactivation, it might |