Re: [PATCH v2] mm/page_alloc: Fix sleeping function called in case of irqsdisable

[Zhang, Qiang]

________________________________________
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Sent: Tuesday, 6 July 2021 16:33
To: Zhang, Qiang
Cc: syzbot+0123a2b8f9e623d5b443@xxxxxxxxxxxxxxxxxxxxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx; alobakin@xxxxx; songmuchun@xxxxxxxxxxxxx; wangqing@xxxxxxxx; linux-mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: [PATCH v2] mm/page_alloc: Fix sleeping function called in case of irqsdisable

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On Tue, Jul 06, 2021 at 03:57:54PM +0800, qiang.zhang@xxxxxxxxxxxxx wrote:
> From: Zqiang <qiang.zhang@xxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxxxxxxxxxxxx
> Suggested-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> Signed-off-by: Zqiang <qiang.zhang@xxxxxxxxxxxxx>

>Same comment as v1 with respect to the impact of enabling/disabling IRQs
>for each page allocated -- it hurts performance regardless of whether
>page owner is enabled or not. If returning a single page is undesirable
>then a slightly different alternative is to only enable IRQs if page
>owner is set and then goto "Attempt the batch allocation" to reacquire
>the lock and lookup pcp.
>

Thank you for your explanation. I didn't take performance into consideration.

>--
>Mel Gorman
>SUSE Labs