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From: Christoph Hellwig <hch@lst.de>
To: Ritesh Harjani <ritesh.list@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Christian Brauner <brauner@kernel.org>,
	"Darrick J. Wong" <djwong@kernel.org>,
	Chandan Babu R <chandan.babu@oracle.com>,
	Zhang Yi <yi.zhang@huaweicloud.com>,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 04/13] iomap: drop the obsolete PF_MEMALLOC check in iomap_do_writepage
Date: Mon, 27 Nov 2023 07:41:07 +0100	[thread overview]
Message-ID: <20231127064107.GA27540@lst.de> (raw)
In-Reply-To: <875y1nsnsj.fsf@doe.com>

On Mon, Nov 27, 2023 at 12:09:08PM +0530, Ritesh Harjani wrote:
> Nice cleanup. As you explained, iomap_do_writepage() never gets called
> from memory reclaim context. So it is unused code which can be removed. 
> 
> However, there was an instance when this WARN was hit by wrong
> usage of PF_MEMALLOC flag [1], which was caught due to WARN_ON_ONCE.
> 
> [1]: https://lore.kernel.org/linux-xfs/20200309185714.42850-1-ebiggers@kernel.org/
> 
> Maybe we can just have a WARN_ON_ONCE() and update the comments?
> We anyway don't require "goto redirty" anymore since we will never
> actually get called from reclaim context.

Well, xfs/iomap never really cared about the flag, just that it didn't
get called from direct reclaim or kswapd.  If we think such a WARN_ON
is still useful, the only caller of it in do_writepages might be a better
place.


  reply	other threads:[~2023-11-27  6:41 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-26 12:47 RFC: map multiple blocks per ->map_blocks in iomap writeback Christoph Hellwig
2023-11-26 12:47 ` [PATCH 01/13] iomap: clear the per-folio dirty bits on all writeback failures Christoph Hellwig
2023-11-27  3:47   ` Ritesh Harjani
2023-11-27  6:29     ` Christoph Hellwig
2023-11-26 12:47 ` [PATCH 02/13] iomap: treat inline data in iomap_writepage_map as an I/O error Christoph Hellwig
2023-11-27  5:01   ` Ritesh Harjani
2023-11-27  6:33     ` Christoph Hellwig
2023-11-29  4:40       ` Darrick J. Wong
2023-11-29  5:39         ` Christoph Hellwig
2023-11-26 12:47 ` [PATCH 03/13] iomap: move the io_folios field out of struct iomap_ioend Christoph Hellwig
2023-11-27  5:33   ` Ritesh Harjani
2023-11-29  4:41   ` Darrick J. Wong
2023-11-26 12:47 ` [PATCH 04/13] iomap: drop the obsolete PF_MEMALLOC check in iomap_do_writepage Christoph Hellwig
2023-11-27  6:39   ` Ritesh Harjani
2023-11-27  6:41     ` Christoph Hellwig [this message]
2023-11-29  4:45       ` Darrick J. Wong
2023-11-26 12:47 ` [PATCH 05/13] iomap: factor out a iomap_writepage_handle_eof helper Christoph Hellwig
2023-11-27  6:57   ` Ritesh Harjani
2023-11-27  7:02     ` Ritesh Harjani
2023-11-27  7:12       ` Christoph Hellwig
2023-11-29  4:48         ` Darrick J. Wong
2023-11-26 12:47 ` [PATCH 06/13] iomap: move all remaining per-folio logic into xfs_writepage_map Christoph Hellwig
2023-11-27  7:36   ` Ritesh Harjani
2023-11-27 19:20   ` Josef Bacik
2023-11-29  4:50   ` Darrick J. Wong
2023-11-26 12:47 ` [PATCH 07/13] iomap: clean up the iomap_new_ioend calling convention Christoph Hellwig
2023-11-27  7:43   ` Ritesh Harjani
2023-11-27  8:13     ` Christoph Hellwig
2023-11-29  4:51       ` Darrick J. Wong
2023-11-26 12:47 ` [PATCH 08/13] iomap: move the iomap_sector sector calculation out of iomap_add_to_ioend Christoph Hellwig
2023-11-27  9:54   ` Ritesh Harjani
2023-11-27 13:54     ` Christoph Hellwig
2023-11-29  4:53       ` Darrick J. Wong
2023-11-29  5:42         ` Christoph Hellwig
2023-11-26 12:47 ` [PATCH 09/13] iomap: don't chain bios Christoph Hellwig
2023-11-27 12:53   ` Zhang Yi
2023-11-27 13:51     ` Christoph Hellwig
2023-11-29  4:59   ` Darrick J. Wong
2023-11-29  5:40     ` Christoph Hellwig
2023-11-26 12:47 ` [PATCH 10/13] iomap: only call mapping_set_error once for each failed bio Christoph Hellwig
2023-11-29  5:03   ` Darrick J. Wong
2023-11-29  5:41     ` Christoph Hellwig
2023-11-26 12:47 ` [PATCH 11/13] iomap: factor out a iomap_writepage_map_block helper Christoph Hellwig
2023-11-29  5:06   ` Darrick J. Wong
2023-11-26 12:47 ` [PATCH 12/13] iomap: submit ioends immediately Christoph Hellwig
2023-11-29  5:14   ` Darrick J. Wong
2023-11-26 12:47 ` [PATCH 13/13] iomap: map multiple blocks at a time Christoph Hellwig
2023-11-29  5:25   ` Darrick J. Wong
2023-11-29  5:44     ` Christoph Hellwig

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