linux-kernel - Re: [PATCH v5 6/6] mm: handle userfaults under VMA lock

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Message-ID: <ZJxulItq9iHi2Uew@x1n>
Date:   Wed, 28 Jun 2023 13:32:04 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     akpm@...ux-foundation.org, willy@...radead.org, hannes@...xchg.org,
        mhocko@...e.com, josef@...icpanda.com, jack@...e.cz,
        ldufour@...ux.ibm.com, laurent.dufour@...ibm.com,
        michel@...pinasse.org, liam.howlett@...cle.com, jglisse@...gle.com,
        vbabka@...e.cz, minchan@...gle.com, dave@...olabs.net,
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        apopple@...dia.com, ying.huang@...el.com, david@...hat.com,
        yuzhao@...gle.com, dhowells@...hat.com, hughd@...gle.com,
        viro@...iv.linux.org.uk, brauner@...nel.org,
        pasha.tatashin@...een.com, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-team@...roid.com
Subject: Re: [PATCH v5 6/6] mm: handle userfaults under VMA lock

On Wed, Jun 28, 2023 at 10:25:29AM -0700, Suren Baghdasaryan wrote:
> Enable handle_userfault to operate under VMA lock by releasing VMA lock
> instead of mmap_lock and retrying. Note that FAULT_FLAG_RETRY_NOWAIT
> should never be used when handling faults under per-VMA lock protection
> because that would break the assumption that lock is dropped on retry.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>

Maybe the sanitize_fault_flags() changes suite more in patch 3, but not a
big deal I guess.

Acked-by: Peter Xu <peterx@...hat.com>

Thanks!

-- 
Peter Xu