From: "Stephen C. Tweedie" <sct@redhat.com>
To: Rik van Riel <riel@nl.linux.org>
Cc: Andrea Arcangeli <andrea@suse.de>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Linux MM <linux-mm@kvack.org>, Stephen Tweedie <sct@redhat.com>,
Linux Kernel <linux-kernel@vger.rutgers.edu>
Subject: Re: 2.2.1{3,4,5pre*} VM bug found
Date: Thu, 27 Jan 2000 19:09:59 +0000 (GMT) [thread overview]
Message-ID: <14480.38919.179054.61948@dukat.scot.redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.10.10001260146290.1373-100000@mirkwood.dummy.home>
Hi,
On Wed, 26 Jan 2000 01:48:43 +0100 (CET), Rik van Riel
<riel@nl.linux.org> said:
> The problem in this case is that schedule() may be called
> from within get_page(GFP_KERNEL). This already was possible
> in 2.2.14 and before (if the task had to wait for I/O on
> try_to_free_pages()), but the explicit schedule() in my
> stuff in 2.2.15pre4 amplified the problem and made it
> visible.
It's not only possible, it is explicitly legal. It always has been.
You _must_ call it with GFP_ATOMIC if you can't afford to block (or,
alternatively, call it without __GFP_IO, or with the PF_MEMALLOC flag).
> A fix for this problem is in one of my other emails
It's not a problem. If callers are expecting GFP_KERNEL to be atomic,
then _that_ is a problem, but it is perfectly all right for GFP_KERNEL
allocations to block.
--Stephen
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next prev parent reply other threads:[~2000-01-27 19:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-01-25 3:27 2.2.1{3,4,5pre*} VM bug found Rik van Riel
2000-01-25 18:15 ` Andrea Arcangeli
2000-01-26 0:48 ` Rik van Riel
2000-01-27 19:09 ` Stephen C. Tweedie [this message]
2000-01-27 19:07 ` Stephen C. Tweedie
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