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From: Matthew Wilcox <[email protected]>
To: Jens Axboe <[email protected]>
Cc: "Darrick J. Wong" <[email protected]>,
	Christian Brauner <[email protected]>,
	Dave Chinner <[email protected]>, Hao Xu <[email protected]>,
	[email protected],
	Dominique Martinet <[email protected]>,
	Pavel Begunkov <[email protected]>,
	Alexander Viro <[email protected]>,
	Stefan Roesch <[email protected]>, Clay Harris <[email protected]>,
	[email protected], Wanpeng Li <[email protected]>
Subject: Re: [PATCH 3/5] io_uring: add support for getdents
Date: Tue, 1 Aug 2023 02:01:59 +0100	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On Mon, Jul 31, 2023 at 06:49:45PM -0600, Jens Axboe wrote:
> On 7/31/23 6:47?PM, Matthew Wilcox wrote:
> > On Mon, Jul 31, 2023 at 06:28:02PM -0600, Jens Axboe wrote:
> >> It's also not an absolute thing, like memory allocations are. It's
> >> perfectly fine to grab a mutex under NOWAIT issue. What you should not
> >> do is grab a mutex that someone else can grab while waiting on IO. This
> >> kind of extra context is only available in the code in question, not
> >> generically for eg mutex locking.
> > 
> > Is that information documented somewhere?  I didn't know that was the
> > rule, and I wouldn't be surprised if that's news to several of the other
> > people on this thread.
> 
> I've mentioned it in various threads, but would probably be good to
> write down somewhere if that actually makes more people see it. I'm
> dubious, but since it applies to NOWAIT in general, would be a good
> thing to do regardless. And then at least I could point to that rather
> than have to write up a long description every time.

Would be good to include whether it's OK to wait on a mutex that's held
by another thread that's allocating memory without __GFP_NOFS (since
obviously that can block on I/O)

  reply	other threads:[~2023-08-01  1:02 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-18 13:21 [PATCH v4 0/5] io_uring getdents Hao Xu
2023-07-18 13:21 ` [PATCH 1/5] fs: split off vfs_getdents function of getdents64 syscall Hao Xu
2023-07-18 13:21 ` [PATCH 2/5] vfs_getdents/struct dir_context: add flags field Hao Xu
2023-07-18 13:21 ` [PATCH 3/5] io_uring: add support for getdents Hao Xu
2023-07-19  8:56   ` Hao Xu
2023-07-26 15:00   ` Christian Brauner
2023-07-27 11:51     ` Hao Xu
2023-07-27 14:27       ` Christian Brauner
2023-07-27 15:12         ` Pavel Begunkov
2023-07-27 15:52           ` Christian Brauner
2023-07-27 16:17             ` Pavel Begunkov
2023-07-27 16:28               ` Christian Brauner
2023-07-31  1:58                 ` Dave Chinner
2023-07-31  7:34                   ` Hao Xu
2023-07-31  7:50                     ` Christian Brauner
2023-07-31  7:40                   ` Christian Brauner
2023-07-30 18:02         ` Hao Xu
2023-07-31  8:18           ` Christian Brauner
2023-07-31  9:31             ` Hao Xu
2023-07-31  1:33         ` Dave Chinner
2023-07-31  8:13           ` Christian Brauner
2023-07-31 15:26             ` Darrick J. Wong
2023-07-31 22:18               ` Dave Chinner
2023-08-01  0:28               ` Jens Axboe
2023-08-01  0:47                 ` Matthew Wilcox
2023-08-01  0:49                   ` Jens Axboe
2023-08-01  1:01                     ` Matthew Wilcox [this message]
2023-08-01  7:00                       ` Christian Brauner
2023-08-01  6:59                     ` Christian Brauner
2023-08-01  7:17                 ` Christian Brauner
2023-08-08  4:34                 ` Hao Xu
2023-08-08  5:18                   ` Hao Xu
2023-08-08  9:33                 ` Hao Xu
2023-08-08 22:55                   ` Jens Axboe
2023-08-01 18:39             ` Hao Xu
2023-07-18 13:21 ` [PATCH 4/5] xfs: add NOWAIT semantics for readdir Hao Xu
2023-07-19  2:35   ` kernel test robot
2023-07-18 13:21 ` [PATCH RFC 5/5] disable fixed file for io_uring getdents for now Hao Xu
2023-07-26 14:23   ` Christian Brauner
2023-07-27 12:09     ` Hao Xu
2023-07-19  6:04 ` [PATCH v4 0/5] io_uring getdents Christian Brauner

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