netdev - Re: [PATCH 12/29] xfs: enforce GFP_NOIO implicitly during nowait time update

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZOi4oV7Ho3y0106O@casper.infradead.org>
Date: Fri, 25 Aug 2023 15:20:17 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Hao Xu <hao.xu@...ux.dev>
Cc: io-uring@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
	Dominique Martinet <asmadeus@...ewreck.org>,
	Pavel Begunkov <asml.silence@...il.com>,
	Christian Brauner <brauner@...nel.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Stefan Roesch <shr@...com>, Clay Harris <bugs@...ycon.org>,
	Dave Chinner <david@...morbit.com>,
	"Darrick J . Wong" <djwong@...nel.org>,
	linux-fsdevel@...r.kernel.org, linux-xfs@...r.kernel.org,
	linux-ext4@...r.kernel.org, linux-cachefs@...hat.com,
	ecryptfs@...r.kernel.org, linux-nfs@...r.kernel.org,
	linux-unionfs@...r.kernel.org, bpf@...r.kernel.org,
	netdev@...r.kernel.org, linux-s390@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
	linux-btrfs@...r.kernel.org, codalist@...a.cs.cmu.edu,
	linux-f2fs-devel@...ts.sourceforge.net, cluster-devel@...hat.com,
	linux-mm@...ck.org, linux-nilfs@...r.kernel.org,
	devel@...ts.orangefs.org, linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org, linux-mtd@...ts.infradead.org,
	Wanpeng Li <wanpengli@...cent.com>
Subject: Re: [PATCH 12/29] xfs: enforce GFP_NOIO implicitly during nowait
 time update

On Fri, Aug 25, 2023 at 09:54:14PM +0800, Hao Xu wrote:
> +++ b/fs/xfs/xfs_iops.c
> @@ -1037,6 +1037,8 @@ xfs_vn_update_time(
>  	int			log_flags = XFS_ILOG_TIMESTAMP;
>  	struct xfs_trans	*tp;
>  	int			error;
> +	int			old_pflags;
> +	bool			nowait = flags & S_NOWAIT;
>  
>  	trace_xfs_update_time(ip);
>  
> @@ -1049,13 +1051,18 @@ xfs_vn_update_time(
>  		log_flags |= XFS_ILOG_CORE;
>  	}
>  
> +	if (nowait)
> +		old_pflags = memalloc_noio_save();
> +
>  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);

This is an abuse of the memalloc_noio_save() interface.  You shouldn't
be setting it around individual allocations; it's the part of the kernel
which decides "I can't afford to do I/O" that should be setting it.
In this case, it should probably be set by io_uring, way way way up at
the top.

But Jens didn't actually answer my question about that:

https://lore.kernel.org/all/ZMhZh2EYPMH1wIXX@casper.infradead.org/