From: Andrew Morton <akpm@linux-foundation.org>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-kselftest@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
Hugh Dickins <hughd@google.com>, Vlastimil Babka <vbabka@suse.cz>,
Peter Xu <peterx@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Jason Gunthorpe <jgg@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH v1 4/7] mm/ksm: fix KSM COW breaking with userfaultfd-wp via FAULT_FLAG_UNSHARE
Date: Fri, 30 Sep 2022 15:27:42 -0700 [thread overview]
Message-ID: <20220930152742.55ee9c25b89ba483ec211be8@linux-foundation.org> (raw)
In-Reply-To: <20220930141931.174362-5-david@redhat.com>
On Fri, 30 Sep 2022 16:19:28 +0200 David Hildenbrand <david@redhat.com> wrote:
> Let's stop breaking COW via a fake write fault and let's use
> FAULT_FLAG_UNSHARE instead. This avoids any wrong side effects of the fake
> write fault, such as mapping the PTE writable and marking the pte
> dirty/softdirty.
>
> Also, this fixes KSM interaction with userfaultfd-wp: when we have a KSM
> page that's write-protected by userfaultfd, break_ksm()->handle_mm_fault()
> will fail with VM_FAULT_SIGBUS and will simpy return in break_ksm() with 0.
> The warning in dmesg indicates this wrong handling:
We're at -rc7. I'd prefer to avoid merging larger patchsets at this
time.
Is there some minimal fix for 6.0 and -stable? Or is the problem
non-serious enough to only fix it in 6.1 and later?
next prev parent reply other threads:[~2022-09-30 22:27 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-30 14:19 [PATCH v1 0/7] mm/ksm: break_ksm() cleanups and fixes David Hildenbrand
2022-09-30 14:19 ` [PATCH v1 1/7] selftests/vm: add test to measure MADV_UNMERGEABLE performance David Hildenbrand
2022-10-05 20:27 ` Peter Xu
2022-09-30 14:19 ` [PATCH v1 2/7] mm/ksm: simplify break_ksm() to not rely on VM_FAULT_WRITE David Hildenbrand
2022-10-05 20:29 ` Peter Xu
2022-09-30 14:19 ` [PATCH v1 3/7] mm: remove VM_FAULT_WRITE David Hildenbrand
2022-10-05 20:29 ` Peter Xu
2022-09-30 14:19 ` [PATCH v1 4/7] mm/ksm: fix KSM COW breaking with userfaultfd-wp via FAULT_FLAG_UNSHARE David Hildenbrand
2022-09-30 22:27 ` Andrew Morton [this message]
2022-10-01 8:13 ` David Hildenbrand
2022-10-05 20:35 ` Peter Xu
2022-10-06 9:29 ` David Hildenbrand
2022-10-06 19:04 ` Peter Xu
2022-10-20 10:05 ` David Hildenbrand
2022-09-30 14:19 ` [PATCH v1 5/7] mm/pagewalk: add walk_page_range_vma() David Hildenbrand
2022-10-05 20:42 ` Peter Xu
2022-10-06 9:35 ` David Hildenbrand
2022-09-30 14:19 ` [PATCH v1 6/7] mm/ksm: convert break_ksm() to use walk_page_range_vma() David Hildenbrand
2022-10-05 21:00 ` Peter Xu
2022-10-06 9:20 ` David Hildenbrand
2022-10-06 19:28 ` Peter Xu
2022-10-21 9:11 ` David Hildenbrand
2022-10-20 8:59 ` David Hildenbrand
2022-09-30 14:19 ` [PATCH v1 7/7] mm/gup: remove FOLL_MIGRATION David Hildenbrand
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=20220930152742.55ee9c25b89ba483ec211be8@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=aarcange@redhat.com \
--cc=david@redhat.com \
--cc=hughd@google.com \
--cc=jgg@nvidia.com \
--cc=jhubbard@nvidia.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=peterx@redhat.com \
--cc=shuah@kernel.org \
--cc=vbabka@suse.cz \
--cc=willy@infradead.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).