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AJvYcCVWVzq/WdxB4DgqNQRmjCmBmz9YRj4/O5fYi4C0bB5kO+vAqNKG0fKTujLsL/pnpZvJS3Vv+kVxsQ==@kvack.org X-Gm-Message-State: AOJu0YydhNe04oGuJIaCkuAvVgACUKBjWKZGjC2T6Ub4E6OixGvxabJZ 1LzEfzuf6mbF+0xNOgrWgkcO44fOlqC8R9g7H5MM9ZryHav6AR5poZLycOCLw3W35fJw7+/OzCo rSNOKnnmyaKjjNqcNfuR9j1NxCNI= X-Gm-Gg: ASbGncsVW4GbZilf4AjC1u4rEmONdp5RtmxzmgmpC3gPnmoxP3SmCH7JUNiAP9uQiOL dWbm5s2SwQJu1I68WCYK8CrVoTv3CmNUG2nbo0h4ofkcsJK/1rZM0LZn1yP14M5P04qcagFYprx Vuu6qqKXtZ6pkfluAVWIrpr/w= X-Google-Smtp-Source: AGHT+IEtBMoCTUav6TSmsKLpwW3a3MxoLkSWBfm5obvrcgUQcp2uu4q4pzqh/afdF4jNJX3Uzx31+bQWBYx2Js2h/d4= X-Received: by 2002:a05:6000:dcf:b0:38d:c44a:a64b with SMTP id ffacd0b85a97d-390cc63c045mr7606159f8f.48.1740590121799; Wed, 26 Feb 2025 09:15:21 -0800 (PST) MIME-Version: 1.0 References: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> <20250214-slub-percpu-caches-v2-3-88592ee0966a@suse.cz> <20250226170053.lxpreaegz5tysef7@offworld> In-Reply-To: <20250226170053.lxpreaegz5tysef7@offworld> From: Alexei Starovoitov Date: Wed, 26 Feb 2025 09:15:10 -0800 X-Gm-Features: AQ5f1Jp-y9BTFtvA4Pj5PaiujmHZngx-Du8gcaN_n9QesEj3-kDANfPP_INIgoo Message-ID: Subject: Re: [PATCH RFC v2 03/10] locking/local_lock: Introduce localtry_lock_t To: Vlastimil Babka , Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm , LKML , rcu@vger.kernel.org, maple-tree@lists.infradead.org, Sebastian Andrzej Siewior , Alexei Starovoitov Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: E48ED1C000D X-Stat-Signature: cjg8kf6mcb6ue1jb3asrkterru9qsayp X-HE-Tag: 1740590123-277061 X-HE-Meta: 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 fqRZrjZq 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, 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 Wed, Feb 26, 2025 at 9:01=E2=80=AFAM Davidlohr Bueso = wrote: > > On Fri, 14 Feb 2025, Vlastimil Babka wrote: > > >From: Sebastian Andrzej Siewior > > > >In !PREEMPT_RT local_lock_irqsave() disables interrupts to protect > >critical section, but it doesn't prevent NMI, so the fully reentrant > >code cannot use local_lock_irqsave() for exclusive access. > > > >Introduce localtry_lock_t and localtry_lock_irqsave() that > >disables interrupts and sets acquired=3D1, so localtry_lock_irqsave() > >from NMI attempting to acquire the same lock will return false. > > > >In PREEMPT_RT local_lock_irqsave() maps to preemptible spin_lock(). > >Map localtry_lock_irqsave() to preemptible spin_trylock(). > >When in hard IRQ or NMI return false right away, since > >spin_trylock() is not safe due to PI issues. > > > >Note there is no need to use local_inc for acquired variable, > >since it's a percpu variable with strict nesting scopes. > > > > LGTM. > > Acked-by: Davidlohr Bueso Thanks for the review. Do you mind if I apply your ack to the latest version of this patch? https://lore.kernel.org/bpf/20250222024427.30294-2-alexei.starovoitov@gmail= .com/