* Re: [PATCH v4 12/14] userfaultfd: add UFFDIO_SET_MODE for runtime sync/async toggle
[not found] ` <20260525124220.5336F1F00A3A@smtp.kernel.org>
@ 2026-05-25 15:40 ` Kiryl Shutsemau
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From: Kiryl Shutsemau @ 2026-05-25 15:40 UTC (permalink / raw)
To: sashiko-reviews
Cc: kvm, akpm, rppt, peterx, david, ljs, surenb, vbabka, Liam.Howlett,
ziy, corbet, skhan, seanjc, pbonzini, jthoughton, aarcange, sj,
usama.arif, linux-mm, linux-kernel, linux-doc, linux-kselftest,
kernel-team
On Mon, May 25, 2026 at 12:42:20PM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
> - [High] The userfaultfd_set_mode function iterates over an external mm_struct's VMAs without verifying address space stability.
Pre-existing pattern across UFFD ioctls -- userfaultfd_register(),
userfaultfd_unregister(), userfaultfd_rwprotect() all iterate VMAs
after mmget_not_zero() + mmap_write_lock() without
check_stable_address_space().
If the XA_ZERO_ENTRY hazard is real, it applies to all of those too;
leave as a separate audit follow-up.
> - [Low] Lockless read of ctx->features races with its own WRITE_ONCE
> update, causing a data race.
Will be fixed in v5:
- !(ctx->features & UFFD_FEATURE_RWP))
+ !(userfaultfd_features(ctx) & UFFD_FEATURE_RWP))
> --
> Sashiko AI review · https://sashiko.dev/#/patchset/20260525113737.1942478-1-kas@kernel.org?part=12
--
Kiryl Shutsemau / Kirill A. Shutemov
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