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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: D0B834000B X-Stat-Signature: caiz3zrsee86ewcig1uax114obhyukhm X-Rspam-User: X-HE-Tag: 1734081110-663891 X-HE-Meta: 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 WwZyVWd4 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000387, 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 Fri, Dec 13, 2024 at 01:27:00AM +0100, Linus Walleij wrote: > On Wed, Dec 11, 2024 at 4:22 PM Sebastian Andrzej Siewior > wrote: > > On 2024-12-11 14:29:29 [+0100], Linus Walleij wrote: > > > So fast GUP is supposed to be lockless, and should just not > > > have this problem. So it can't be addressing gup_fast_pgd_range() > > > right? > > … > > > I'm more asking if HIGHPTE even acquires a spinlock anymore > > > as it is supposed to be "fast"/lockless. If it does, it is clearly violating > > > the "fast" promise of the fast GUP API and should not exist. > > > > This is lockless on x86. The problem is ARM's > > arch_kmap_local_high_get(). This is where the lock is from. > > Aha that calls down to kmap_high_get() that that issues > lock_kmap_any(flags). > > But is it really sound that the "fast" API does this? It feels > like a violation of the whole design of the fast stuff. If there's no way to do it lockless, then it has to take the lock. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!