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Howlett" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: E3DFF1C0007 X-Rspam-User: X-Stat-Signature: nj97zo93j4wcp7xzzcmh4rksskxdkkjx X-Rspamd-Server: rspam09 X-HE-Tag: 1756839897-163207 X-HE-Meta: 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 0L350d5J nKSoyfNOCMOaHFed3acwilQ/P4YqciZNJMsEOKBna8w94ZYHGoXMSLZ2/UJ510F5aEud2guejY49YWGjzW42YLDIb1PEX31Lb5z8amOk2SJ9xkeXbZ7RvnEU4bVc6WJlmS49vt1G6TRhxIE70ASntQ74QKL1xtBz/HETw5V/bozOWBBobgzgU0g5jhw5Xz+lxur8265JhR6JwNVaSpt69t4TftSpIns4ouqfMWiC6AjqVWWyHHO9D/mYay163/yuSZGPzdrMkY/GeUEYYVnqJDvyfc55dK01da+pm X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 2, 2025 at 12:01=E2=80=AFPM David Hildenbrand wrote: > > On 02.09.25 20:59, Lokesh Gidra wrote: > > On Fri, Aug 29, 2025 at 2:04=E2=80=AFAM Lorenzo Stoakes > > wrote: > >> > >> On Fri, Aug 29, 2025 at 10:42:45AM +0200, David Hildenbrand wrote: > >>>>> > >>>>> I do wonder if we can identify this case and handle things differen= tly. > >>>>> > >>>>> Perhaps even saying 'try and get the rmap lock, but if there's "too= much" > >>>>> contention, grab the folio lock. > >>>> > >>>> Can you please elaborate what you mean? Where do you mean we can > >>>> possibly do something like this? > >>>> > >>>> UFFD move only works on PageAnonExclusive folios. So, would it help > >>>> (in terms of avoiding contention) if we were to change the condition= : > >>> > >>> I think we shouldn't be using PAE here. Once could consider using > >>> folio_maybe_mapped_shared(), and assume contention on the folio lock = if it > >>> is maybe mapped shared. > >> > >> Interesting! > >> > >>> > >>> But the real question is with whom we would be contending for the fol= io > >>> lock. > >>> > >>> Is it really other processes mapping that folio? I'm not so sure. > >> > >> Yeah, I might go off and do some research myself on this, actually. Na= il down > >> wehre this might actually happen. > >> > >> Generally I'm softening on this and maybe we're good with the proposed= change. > >> > >> But still want to be super careful here... :) > >> > > Anxiously waiting for your assessment. Fingers crossed :) > > I'd suggest you prepare an RFC patch where you neatly summarize all we > learned so far. :) > Sounds good. Will do. Thanks. > -- > Cheers > > David / dhildenb >