From: no-reply@sashiko.virtuozzo.com
To: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>,
Konstantin Khorenko <khorenko@virtuozzo.com>,
Vasileios Almpanis <vasileios.almpanis@virtuozzo.com>,
Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 3/8] oracle/mm: do not write protect COW mappings when preserving across exec
Date: Wed, 14 Oct 2026 17:20:11 +0000 [thread overview]
Message-ID: <010701a13b6dc15a-8d5ec569-006f-4d6c-9abe-1815ed016675-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261014-b4-prep-khorenko-vstor-149847-2-doexec-pinned-memory-v1-3-36f1120f9b57@virtuozzo.com>
> From: Anthony Yznaga <anthony.yznaga@oracle.com>
>
> A mapping that is pinned for DMA and preserved across exec can incur
> a COW if write protected. The elevated reference count prevents reuse
> of the mapped folio.
>
> Orabug: 38029049
> Suggested-by: Steve Sistare <steven.sistare@oracle.com>
> Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
> Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
> (cherry picked from commit f2e56cc70e62fe07efb71a1e1c2360a78cba5aff)
>
> Taken from Oracle linux-uek branch uek8/u2. Applied cleanly.
>
> This is the fix for the ticket: a FOLL_LONGTERM-pinned anonymous page
> preserved with MADV_DOEXEC was write-protected and lost
> PageAnonExclusive in vma_dup(), so the first write in the new image
> COWed it and the pin kept the old page. The pinned pages now stay
> exclusive and writable in the new mm, and the old mm keeps its own. The
> fixes that follow write protect both again and zap the old mm's mappings
> right after the copy.
>
> Fixes: 9e6d16a6c0a1 ("oracle/mm: introduce VM_EXEC_KEEP")
> https://virtuozzo.atlassian.net/browse/VSTOR-150231
>
> Feature: oracle/mm: MADV_DOEXEC madvise() flag
> Assisted-by: LLM
> Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261014-b4-prep-khorenko-vstor-149847-2-doexec-pinned-memory-v1-0-36f1120f9b57@virtuozzo.com?part=3
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next prev parent reply other threads:[~2026-10-14 17:21 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-14 17:11 [Devel] [PATCH hci-8.1 0/8] mm: keep DMA-pinned MADV_DOEXEC memory working " Konstantin Khorenko
2026-10-14 17:11 ` [Devel] [PATCH hci-8.1 1/8] oracle/mm: fix VM_BUG_ON hit when preserving memory Konstantin Khorenko
2026-10-14 17:16 ` no-reply
2026-10-14 17:11 ` [Devel] [PATCH hci-8.1 2/8] oracle/mm: hold the source mmap write lock when copying PTEs Konstantin Khorenko
2026-10-14 17:15 ` no-reply
2026-10-14 17:11 ` [Devel] [PATCH hci-8.1 3/8] oracle/mm: do not write protect COW mappings when preserving across exec Konstantin Khorenko
2026-10-14 17:20 ` no-reply [this message]
2026-10-14 17:11 ` [Devel] [PATCH hci-8.1 4/8] oracle/mm: write protect preserved PTEs but keep them exclusive Konstantin Khorenko
2026-10-14 17:18 ` no-reply
2026-10-14 17:11 ` [Devel] [PATCH hci-8.1 5/8] oracle/mm: set MMF_HAS_PINNED on the mm receiving preserved pages Konstantin Khorenko
2026-10-14 17:19 ` no-reply
2026-10-14 17:11 ` [Devel] [PATCH hci-8.1 6/8] oracle/mm: zap the preserved ranges of the old mm after copying them Konstantin Khorenko
2026-10-14 17:24 ` no-reply
2026-10-14 17:11 ` [Devel] [PATCH hci-8.1 7/8] exec: protect preserved memory against surviving shared-mm tasks Konstantin Khorenko
2026-10-14 17:24 ` no-reply
2026-10-14 17:11 ` [Devel] [PATCH hci-8.1 8/8] selftests/mm: test memory preservation across exec Konstantin Khorenko
2026-10-14 17:33 ` no-reply
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