From: Oleg Nesterov <oleg@redhat.com>
To: Manfred Spraul <manfred@colorfullife.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
WangYuli <wangyuli@uniontech.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Christian Brauner <brauner@kernel.org>
Subject: Re: [RESEND PATCH] fs/pipe: Introduce a check to skip sleeping processes during pipe read/write
Date: Mon, 30 Dec 2024 16:38:45 +0100 [thread overview]
Message-ID: <20241230153844.GA15134@redhat.com> (raw)
In-Reply-To: <a71a7cad-c007-45be-9fd1-22642b835edd@colorfullife.com>
Hi Manfred,
On 12/29, Manfred Spraul wrote:
>
> Hi Oleg,
>
> On 12/29/24 2:13 PM, Oleg Nesterov wrote:
> >Sorry for the noise...
> >
> >and currently this is fine.
Heh, please see below.
> But if we want to add the wq_has_sleeper()
> >checks into fs/pipe.c then pipe_poll() needs smp_mb() after it calls
> >poll_wait().
> >
> >Agreed?
>
> Yes, agreed.
>
> Just the comment in pipe_poll() was a bit tricky for me.
Well yes, but... It turns out I didn't grep enough.
See fs/splice.c and wakeup_pipe_readers/writers (which should use
wq_has_sleeper() for grep sake). And I don't understand why do these helpers
use key == NULL...
So it seems that pipe_poll() already needs smp_mb() to fix the current code,
at least in theory. I'll recheck and send the patch(es).
Oleg.
next prev parent reply other threads:[~2024-12-30 15:39 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-25 9:42 [RESEND PATCH] fs/pipe: Introduce a check to skip sleeping processes during pipe read/write WangYuli
2024-12-25 13:30 ` Andy Shevchenko
2024-12-25 13:53 ` Kent Overstreet
2024-12-25 16:04 ` Mateusz Guzik
2024-12-25 16:32 ` Kent Overstreet
2024-12-25 17:22 ` Mateusz Guzik
2024-12-25 17:41 ` Kent Overstreet
2024-12-25 15:42 ` WangYuli
2024-12-25 16:00 ` Willy Tarreau
2024-12-25 16:32 ` WangYuli
2024-12-25 16:56 ` Willy Tarreau
2024-12-26 16:00 ` Oleg Nesterov
2024-12-26 19:02 ` Linus Torvalds
2024-12-26 20:11 ` Oleg Nesterov
2024-12-26 20:29 ` Linus Torvalds
2024-12-26 20:57 ` Oleg Nesterov
2024-12-27 15:54 ` Oleg Nesterov
2024-12-27 16:43 ` Oleg Nesterov
2024-12-27 18:39 ` Manfred Spraul
2024-12-28 14:32 ` Oleg Nesterov
2024-12-28 15:22 ` Oleg Nesterov
2024-12-28 16:32 ` Oleg Nesterov
2024-12-28 18:53 ` Manfred Spraul
2024-12-29 11:54 ` Oleg Nesterov
2024-12-28 16:45 ` Manfred Spraul
2024-12-29 11:57 ` Oleg Nesterov
2024-12-29 12:41 ` Manfred Spraul
2024-12-29 13:05 ` Oleg Nesterov
2024-12-29 13:13 ` Oleg Nesterov
2024-12-29 19:54 ` Manfred Spraul
2024-12-30 15:38 ` Oleg Nesterov [this message]
2024-12-31 11:14 ` Manfred Spraul
2024-12-31 19:38 ` Linus Torvalds
2024-12-31 20:24 ` Oleg Nesterov
2024-12-31 22:31 ` Linus Torvalds
2025-01-02 13:57 ` Oleg Nesterov
2025-01-04 21:15 ` RFC: Checkpatch: Introduce list of functions that need memory barriers Manfred Spraul
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