From: Vlastimil Babka <vbabka@suse.cz>
To: Yang Shi <shy828301@gmail.com>
Cc: Jann Horn <jannh@google.com>, John Hubbard <jhubbard@nvidia.com>,
Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>,
kernel list <linux-kernel@vger.kernel.org>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Jan Kara <jack@suse.cz>, stable <stable@vger.kernel.org>
Subject: Re: [PATCH v2] mm/gup: fix try_grab_compound_head() race with split_huge_page()
Date: Thu, 17 Jun 2021 18:09:16 +0200 [thread overview]
Message-ID: <2847e923-2366-6a3b-3d76-4513a01981a0@suse.cz> (raw)
In-Reply-To: <CAHbLzkpa5MQBtYcRPWu4vNDn=Q8SKStQ-9wKYWogqRrMR3Aonw@mail.gmail.com>
On 6/16/21 8:40 PM, Yang Shi wrote:
> On Wed, Jun 16, 2021 at 10:27 AM Vlastimil Babka <vbabka@suse.cz> wrote:
>>
>> On 6/16/21 1:10 AM, Yang Shi wrote:
>> > On Tue, Jun 15, 2021 at 5:10 AM Jann Horn <jannh@google.com> wrote:
>> >>
>> >
>> > It might be possible after Mel's "mm/page_alloc: Allow high-order
>> > pages to be stored on the per-cpu lists" patch
>> > (https://patchwork.kernel.org/project/linux-mm/patch/20210611135753.GC30378@techsingularity.net/).
>>
>> Those would be percpu indeed, but not "lockless, non-atomic", no? They are
>> protected by a local_lock.
>
> The local_lock is *not* a lock on non-PREEMPT_RT kernel IIUC. It
> disables preempt and IRQ. But preempt disable is no-op on non-preempt
> kernel. IRQ disable can guarantee it is atomic context, but I'm not
> sure if it is equivalent to "atomic freelists" in Jann's context.
Hm right, I thought all locks had the acquire/release semantics, but this one is
just a barrier().
next prev parent reply other threads:[~2021-06-17 16:10 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 1:20 [PATCH v2] mm/gup: fix try_grab_compound_head() race with split_huge_page() Jann Horn
2021-06-15 2:00 ` Andrew Morton
2021-06-15 2:36 ` Jann Horn
2021-06-15 2:36 ` Jann Horn
2021-06-15 2:38 ` Jann Horn
2021-06-15 2:38 ` Jann Horn
2021-06-15 6:37 ` John Hubbard
2021-06-15 12:09 ` Jann Horn
2021-06-15 12:09 ` Jann Horn
2021-06-15 23:10 ` Yang Shi
2021-06-15 23:10 ` Yang Shi
2021-06-16 17:27 ` Vlastimil Babka
2021-06-16 18:40 ` Yang Shi
2021-06-16 18:40 ` Yang Shi
2021-06-17 16:09 ` Vlastimil Babka [this message]
2021-06-18 13:25 ` Jason Gunthorpe
2021-06-18 13:50 ` Matthew Wilcox
2021-06-18 14:58 ` Jason Gunthorpe
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