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Tue, 23 May 2023 20:49:10 -0700 (PDT) Received: from localhost ([192.55.46.56]) by smtp.gmail.com with ESMTPSA id qx15-20020a170906fccf00b00965f98eefc1sm5213304ejb.116.2023.05.23.20.49.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 May 2023 20:49:10 -0700 (PDT) Date: Wed, 24 May 2023 11:48:59 +0800 From: Zhi Wang To: Alistair Popple Cc: Andrew Morton , will@kernel.org, catalin.marinas@arm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, robin.murphy@arm.com, nicolinc@nvidia.com, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, jgg@nvidia.com, John Hubbard , Sean Christopherson Subject: Re: [PATCH 1/2] mmu_notifiers: Restore documentation for .invalidate_range() Message-ID: <20230524114859.000016e3.zhi.wang.linux@gmail.com> In-Reply-To: <3cece716fc09724793aa832e755abfc9d70a8bb3.1684892404.git-series.apopple@nvidia.com> References: <3cece716fc09724793aa832e755abfc9d70a8bb3.1684892404.git-series.apopple@nvidia.com> X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: CBA8F4000A X-Rspam-User: X-Stat-Signature: pcpr6ibiyifipt5f9hmj6wcx5rngjm4o X-Rspamd-Server: rspam03 X-HE-Tag: 1684900152-701584 X-HE-Meta: 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 BXQQ6/rg 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 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: On Wed, 24 May 2023 11:47:28 +1000 Alistair Popple wrote: It is actually commit 4e15a073a168 ("Revert "mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks"")'s problem. It tries to revert commit 5ff7091f5a2c but forgets to get back this piece of comment. It would be better to have a Fixes tag in the commit message. > The .invalidate_range() callback is called by > mmu_notifier_invalidate_range() which is often called while holding > the ptl spin-lock. Therefore any implementations of this callback must > not sleep. This was originally documented when the call back was added > in commit 0f0a327fa12c ("mmu_notifier: add the callback for > mmu_notifier_invalidate_range()") but appears to have been > inadvertently removed by commit 5ff7091f5a2c ("mm, mmu_notifier: > annotate mmu notifiers with blockable invalidate callbacks"). > > Restore the comment to make it clear that .invalidate_range() > callbacks may not sleep. > > Signed-off-by: Alistair Popple > --- > include/linux/mmu_notifier.h | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h > index 64a3e05..447d757 100644 > --- a/include/linux/mmu_notifier.h > +++ b/include/linux/mmu_notifier.h > @@ -200,6 +200,9 @@ struct mmu_notifier_ops { > * external TLB range needs to be flushed. For more in depth > * discussion on this see Documentation/mm/mmu_notifier.rst > * > + * The invalidate_range() function is called under the ptl > + * spin-lock and not allowed to sleep. > + * > * Note that this function might be called with just a sub-range > * of what was passed to invalidate_range_start()/end(), if > * called between those functions. > > base-commit: 44c026a73be8038f03dbdeef028b642880cf1511