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References: <20210706032907.1276-1-qiang.zhang@windriver.com>
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From:   Muchun Song <songmuchun@bytedance.com>
Date:   Tue, 6 Jul 2021 14:50:04 +0800
Message-ID: <CAMZfGtVB-UQV0i4_mrRrt59iWFZbchm1FtT_TFhaE6Bmp43Hfw@mail.gmail.com>
Subject: Re: [External] [PATCH] mm/page_alloc: Fix sleeping function called in
 case of irqsdisable.
To:     qiang.zhang@windriver.com
Cc:     mgorman@techsingularity.net,
        Andrew Morton <akpm@linux-foundation.org>, alobakin@pm.me,
        wangqing@vivo.com,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
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Precedence: bulk

On Tue, Jul 6, 2021 at 11:29 AM <qiang.zhang@windriver.com> wrote:
>
> From: Zqiang <qiang.zhang@windriver.com>
>
> BUG: sleeping function called from invalid context at mm/page_alloc.c:5179
> in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 1, name: swapper/0
> .....
> __dump_stack lib/dump_stack.c:79 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:96
>  ___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:9153
>  prepare_alloc_pages+0x3da/0x580 mm/page_alloc.c:5179
>  __alloc_pages+0x12f/0x500 mm/page_alloc.c:5375
>  alloc_page_interleave+0x1e/0x200 mm/mempolicy.c:2147
>  alloc_pages+0x238/0x2a0 mm/mempolicy.c:2270
>  stack_depot_save+0x39d/0x4e0 lib/stackdepot.c:303
>  save_stack+0x15e/0x1e0 mm/page_owner.c:120
>  __set_page_owner+0x50/0x290 mm/page_owner.c:181
>  prep_new_page mm/page_alloc.c:2445 [inline]
>  __alloc_pages_bulk+0x8b9/0x1870 mm/page_alloc.c:5313
>  alloc_pages_bulk_array_node include/linux/gfp.h:557 [inline]
>  vm_area_alloc_pages mm/vmalloc.c:2775 [inline]
>  __vmalloc_area_node mm/vmalloc.c:2845 [inline]
>  __vmalloc_node_range+0x39d/0x960 mm/vmalloc.c:2947
>  __vmalloc_node mm/vmalloc.c:2996 [inline]
>  vzalloc+0x67/0x80 mm/vmalloc.c:3066
>
> If the PAGE_OWNER is enabled, in __set_page_owner(), the pages will be
> allocated to save calltrace info, due to the allocated action is executed
> under irq disable(pagesets.lock be held), if the gfp variable contains
> the flag that causes sleep, will trigger above information. the
> prep_new_page() is not need to disable irq for protection, fix it through
> enable irq before call prep_new_page().
>
> Fixes: 0f87d9d30f21 ("mm/page_alloc: add an array-based interface to the bulk page allocator")
> Reported-by: syzbot+0123a2b8f9e623d5b443@syzkaller.appspotmail.com
> Signed-off-by: Zqiang <qiang.zhang@windriver.com>
> ---
>  mm/page_alloc.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index d6e94cc8066c..8d7f0f5ce891 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5309,12 +5309,14 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
>                 }
>                 nr_account++;
>
> +               local_unlock_irqrestore(&pagesets.lock, flags);
>                 prep_new_page(page, 0, gfp, 0);
>                 if (page_list)
>                         list_add(&page->lru, page_list);
>                 else
>                         page_array[nr_populated] = page;
>                 nr_populated++;
> +               local_lock_irqsave(&pagesets.lock, flags);

Because pagesets.lock is relocked here, the current
thread can be scheduled to another CPU. The @pcp
and @pcp_list need to be reloaded. Otherwise, it is
broken in the next loop.

Thanks.

>         }
>
>         local_unlock_irqrestore(&pagesets.lock, flags);
> --
> 2.17.1
>