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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Christoph Lameter <cl@linux.com>
Cc: rppt@linux.ibm.com, Matthew Wilcox <willy@infradead.org>,
	Hugh Dickins <hughd@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	bhe@redhat.com, Michal Hocko <mhocko@suse.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Andrea Arcangeli <aarcange@redhat.com>,
	david@redhat.com, mgorman@techsingularity.net,
	David Herrmann <dh.herrmann@gmail.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	kan.liang@intel.com, Andi Kleen <ak@linux.intel.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Peter Zijlstra <peterz@infradead.org>,
	Nick Piggin <npiggin@gmail.com>,
	pifang@redhat.com,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org
Subject: Re: [PATCHi v2] mm: put_and_wait_on_page_locked() while page is migrated
Date: Tue, 27 Nov 2018 08:58:30 -0800	[thread overview]
Message-ID: <CAHk-=wisu7SHwHYo6TKo6t5CM6Da66jGsMgXKdrfNa-fDzdP5g@mail.gmail.com> (raw)
In-Reply-To: <010001675613a406-89de05df-ccf6-4bfa-ae3b-6f94148d514a-000000@email.amazonses.com>

On Tue, Nov 27, 2018 at 8:49 AM Christopher Lameter <cl@linux.com> wrote:
>
> A process has no refcount on a page struct and is waiting for it to become
> unlocked? Why? Should it not simply ignore that page and continue?

The problem isn't that you can just "continue".

You need to *retry*.

And you can't just busy-loop. You want to wait until the page state
has changed, and _then_ retry.

                  Linus

  parent reply	other threads:[~2018-11-27 16:58 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-25  3:21 [PATCH] " Hugh Dickins
2018-11-25  4:07 ` Andrea Arcangeli
2018-11-25 18:30 ` Linus Torvalds
2018-11-26  3:29   ` Hugh Dickins
2018-11-26 19:27     ` Tim Chen
2018-11-26 19:27     ` [PATCHi v2] " Hugh Dickins
2018-11-26 19:30       ` Linus Torvalds
2018-11-26 19:53       ` Michal Hocko
2018-11-26 20:53       ` Matthew Wilcox
2018-11-27 10:56         ` Mike Rapoport
2018-11-27 16:49           ` Christopher Lameter
2018-11-27 16:56             ` Michal Hocko
2018-11-27 16:58             ` Linus Torvalds [this message]
2018-11-27  8:21       ` Vlastimil Babka
2018-11-27 10:58       ` Mike Rapoport
2018-11-27 18:10         ` Matthew Wilcox
2018-11-27 21:08         ` Hugh Dickins
2018-11-27 21:45           ` Mike Rapoport
2018-11-27 22:40           ` Joey Pabalinas
2019-01-10  9:26       ` Vlastimil Babka
2019-01-11  2:08         ` Hugh Dickins
2019-01-11  2:08           ` Hugh Dickins

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