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Subject: Re: [PATCH v2] lockdep: Fix fs_reclaim warning.
From:   Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
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Date:   Mon, 12 Feb 2018 22:46:51 +0900
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Nikolay Borisov wrote:
> I think I've hit another incarnation of that one. The call stack is:
> http://paste.opensuse.org/3f22d013
> 
> The cleaned up callstack of all the ? entries look like:
> 
> __lock_acquire+0x2d8a/0x4b70
> lock_acquire+0x110/0x330
> kmem_cache_alloc+0x29/0x2c0
> __clear_extent_bit+0x488/0x800
> try_release_extent_mapping+0x288/0x3c0
> __btrfs_releasepage+0x6c/0x140
> shrink_page_list+0x227e/0x3110
> shrink_inactive_list+0x414/0xdb0
> shrink_node_memcg+0x7c8/0x1250
> shrink_node+0x2ae/0xb50
> do_try_to_free_pages+0x2b1/0xe20
> try_to_free_pages+0x205/0x570
>  __alloc_pages_nodemask+0xb91/0x2160
> new_slab+0x27a/0x4e0
> ___slab_alloc+0x355/0x610
>  __slab_alloc+0x4c/0xa0
> kmem_cache_alloc+0x22d/0x2c0
> mempool_alloc+0xe1/0x280

Yes, for mempool_alloc() is adding __GFP_NOMEMALLOC | __GFP_NOWARN to gfp_mask.

	gfp_mask |= __GFP_NOMEMALLOC;   /* don't allocate emergency reserves */
	gfp_mask |= __GFP_NORETRY;      /* don't loop in __alloc_pages */
	gfp_mask |= __GFP_NOWARN;       /* failures are OK */

> bio_alloc_bioset+0x1d7/0x830
> ext4_mpage_readpages+0x99f/0x1000 <-
> __do_page_cache_readahead+0x4be/0x840
> filemap_fault+0x8c8/0xfc0
> ext4_filemap_fault+0x7d/0xb0
> __do_fault+0x7a/0x150
> __handle_mm_fault+0x1542/0x29d0
> __do_page_fault+0x557/0xa30
> async_page_fault+0x4c/0x60