linux-kernel - Re: [RESEND PATCH 1/1] block: Set same_page to false in __bio_try_merge

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Date:   Wed, 9 Sep 2020 08:19:07 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Ritesh Harjani <riteshh@...ux.ibm.com>, linux-block@...r.kernel.org
Cc:     linux-fsdevel@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-kernel@...r.kernel.org, hch@...radead.org,
        Shivaprasad G Bhat <sbhat@...ux.ibm.com>,
        Anju T Sudhakar <anju@...ux.vnet.ibm.com>
Subject: Re: [RESEND PATCH 1/1] block: Set same_page to false in
 __bio_try_merge_page if ret is false

On 9/8/20 9:14 PM, Ritesh Harjani wrote:
> If we hit the UINT_MAX limit of bio->bi_iter.bi_size and so we are anyway
> not merging this page in this bio, then it make sense to make same_page
> also as false before returning.
> 
> Without this patch, we hit below WARNING in iomap.
> This mostly happens with very large memory system and / or after tweaking
> vm dirty threshold params to delay writeback of dirty data.
> 
> WARNING: CPU: 18 PID: 5130 at fs/iomap/buffered-io.c:74 iomap_page_release+0x120/0x150
>  CPU: 18 PID: 5130 Comm: fio Kdump: loaded Tainted: G        W         5.8.0-rc3 #6
>  Call Trace:
>   __remove_mapping+0x154/0x320 (unreliable)
>   iomap_releasepage+0x80/0x180
>   try_to_release_page+0x94/0xe0
>   invalidate_inode_page+0xc8/0x110
>   invalidate_mapping_pages+0x1dc/0x540
>   generic_fadvise+0x3c8/0x450
>   xfs_file_fadvise+0x2c/0xe0 [xfs]
>   vfs_fadvise+0x3c/0x60
>   ksys_fadvise64_64+0x68/0xe0
>   sys_fadvise64+0x28/0x40
>   system_call_exception+0xf8/0x1c0
>   system_call_common+0xf0/0x278

Applied, thanks.

-- 
Jens Axboe