From: Jann Horn <jannh@google.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Nicholas Piggin <npiggin@gmail.com>,
Linux-MM <linux-mm@kvack.org>,
Kalesh Singh <kaleshsingh@google.com>,
"Joel Fernandes \(Google\)" <joel@joelfernandes.org>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH 6/6] mm/mremap: hold the rmap lock in write mode when moving page table entries.
Date: Fri, 11 Jun 2021 10:11:19 +0200 [thread overview]
Message-ID: <CAG48ez3=gDRSB02aL84-A54jmPTja3BS0imje-PQywgidRuPxA@mail.gmail.com> (raw)
In-Reply-To: <20210610083549.386085-7-aneesh.kumar@linux.ibm.com>
On Thu, Jun 10, 2021 at 10:35 AM Aneesh Kumar K.V
<aneesh.kumar@linux.ibm.com> wrote:
> To avoid a race between rmap walk and mremap, mremap does take_rmap_locks().
> The lock was taken to ensure that rmap walk don't miss a page table entry due to
> PTE moves via move_pagetables(). The kernel does further optimization of
> this lock such that if we are going to find the newly added vma after the
> old vma, the rmap lock is not taken. This is because rmap walk would find the
> vmas in the same order and if we don't find the page table attached to
> older vma we would find it with the new vma which we would iterate later.
[...]
> Fixes: 2c91bd4a4e2e ("mm: speed up mremap by 20x on large regions")
> Fixes: c49dd3401802 ("mm: speedup mremap on 1GB or larger regions")
probably also "Cc: stable@vger.kernel.org"?
prev parent reply other threads:[~2021-06-11 8:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 8:35 [PATCH 0/6] mremap fixes Aneesh Kumar K.V
2021-06-10 8:35 ` [PATCH 1/6] selftest/mremap_test: Update the test to handle pagesize other than 4K Aneesh Kumar K.V
2021-06-10 8:35 ` [PATCH 2/6] selftest/mremap_test: Avoid crash with static build Aneesh Kumar K.V
2021-06-10 8:35 ` [PATCH 3/6] mm/mremap: Convert huge PUD move to separate helper Aneesh Kumar K.V
2021-06-10 22:03 ` Hugh Dickins
2021-06-10 8:35 ` [PATCH 4/6] mm/mremap: Don't enable optimized PUD move if page table levels is 2 Aneesh Kumar K.V
2021-06-10 8:35 ` [PATCH 5/6] mm/mremap: Use pmd/pud_poplulate to update page table entries Aneesh Kumar K.V
2021-06-10 18:16 ` Linus Torvalds
2021-06-13 9:06 ` Aneesh Kumar K.V
2021-06-13 10:50 ` Matthew Wilcox
2021-06-13 11:13 ` Aneesh Kumar K.V
2021-06-14 5:27 ` Christophe Leroy
2021-06-13 18:53 ` Linus Torvalds
2021-06-10 8:35 ` [PATCH 6/6] mm/mremap: hold the rmap lock in write mode when moving " Aneesh Kumar K.V
2021-06-11 8:11 ` Jann Horn [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAG48ez3=gDRSB02aL84-A54jmPTja3BS0imje-PQywgidRuPxA@mail.gmail.com' \
--to=jannh@google.com \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@linux.ibm.com \
--cc=hughd@google.com \
--cc=joel@joelfernandes.org \
--cc=kaleshsingh@google.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=kirill@shutemov.name \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=npiggin@gmail.com \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).