| Message ID | 20200103085503.1665-1-ahuang12@lenovo.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/1] mm: memcg/slab: Call flush_memcg_workqueue() only if memcg workqueue is valid | expand |
On Fri, Jan 3, 2020 at 12:55 AM Adrian Huang <adrianhuang0701@gmail.com> wrote: > > From: Adrian Huang <ahuang12@lenovo.com> > > 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 > RSP: 0000:ffffffff96203d80 EFLAGS: 00010246 > RAX: ffffffff96203dc8 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: ffffffff96a63120 RSI: ffffffff95efcba2 RDI: ffffffff96203dc0 > RBP: ffffffff96203e08 R08: 0000000000000000 R09: ffffffff962a1828 > R10: 00000000f0000080 R11: dead000000000100 R12: ffff8d8a87c0a770 > R13: dead000000000100 R14: 0000000000000456 R15: ffffffff96203da0 > FS: 0000000000000000(0000) GS:ffff8d8dbd000000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffff8d91cfbff000 CR3: 000000078920a000 CR4: 00000000000406b0 > Call Trace: > ? wait_for_completion+0x51/0x180 > 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(). > > Cc: Shakeel Butt <shakeelb@google.com> > Cc: Joerg Roedel <jroedel@suse.de> > Reported-by: Xiaochun Lee <lixc17@lenovo.com> > Signed-off-by: Adrian Huang <ahuang12@lenovo.com> Fixes: 92ee383f6daab ("mm: fix race between kmem_cache destroy, create and deactivate") Reviewed-by: Shakeel Butt <shakeelb@google.com> Should this be backported to stable trees? > --- > mm/slab_common.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > 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 > -- > 2.17.1 >
> -----Original Message----- > From: Shakeel Butt <shakeelb@google.com> > Sent: Saturday, January 4, 2020 2:33 AM > To: Adrian Huang <adrianhuang0701@gmail.com> > Cc: Christoph Lameter <cl@linux.com>; Pekka Enberg <penberg@kernel.org>; > David Rientjes <rientjes@google.com>; Joonsoo Kim > <iamjoonsoo.kim@lge.com>; Andrew Morton <akpm@linux-foundation.org>; > Linux MM <linux-mm@kvack.org>; Adrian Huang12 <ahuang12@lenovo.com>; > Joerg Roedel <jroedel@suse.de> > Subject: [External] Re: [PATCH 1/1] mm: memcg/slab: Call > flush_memcg_workqueue() only if memcg workqueue is valid > > Fixes: 92ee383f6daab ("mm: fix race between kmem_cache destroy, create and > deactivate") > > Reviewed-by: Shakeel Butt <shakeelb@google.com> Thanks for the review. Really appreciated. Hi Andrew, would it be possible to add Shakeel's Reviewed-by tag to this patch link: http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-slab-call-flush_memcg_workqueue-only-if-memcg-workqueue-is-valid.patch Thanks. > > Should this be backported to stable trees? > -- Adrian
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