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t=1736504268; bh=AIDZ4Zt6VkJjY9xmHhFXsRv+PULsS2USM+JOckKO3HE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MXzRAJhUP9n4r9W4RBKUa7y4zRSAWZBeBDPSpr5GgON9SMB5sDsn1N4b6ztHJpHDO IA363MwDAZg5y/DJULGJ2bnH4qfcsYVALsiP1JalJfszROym9wXZSCc9qauFnLWYkU QTmQBG8fU15LocJ7aVYkZlJTjzX1bHMFzXWnb1oR5vSY1JhQGpg5ckzjQdtIkFi4tE JX93pDUIylkGtUZmmLB1lN4jXsQwWypsUOvjMFeMu/sbP7szji+QjznADXN2dUSXSZ M4Zlh3Q3UPtjlwU+Fg7BXntxA+do5a72mDCVNjLWOoPT7Hir3nlMoBWJkjxxWAqVAC DXh9soyeCoVXQ== Date: Fri, 10 Jan 2025 12:17:37 +0200 From: Mike Rapoport To: Weikang Guo Cc: Christophe Leroy , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] mm/memblock: Modify the default failure behavior of memblock_alloc to panic Message-ID: References: <20250103105158.1350689-1-guoweikang.kernel@gmail.com> <39e6c57c-0a8f-4f4a-b6ae-27f2ef6bb8fa@csgroup.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Queue-Id: 7B1D71C0016 X-Stat-Signature: nxeujqxotqc8coh7efso9ktdrkmwe5qb X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1736504269-84427 X-HE-Meta: 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 FPnCgBUY 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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: List-Subscribe: List-Unsubscribe: On Mon, Jan 06, 2025 at 11:03:38AM +0800, Weikang Guo wrote: > Hi,Christophe, Andrew > > Weikang Guo 于2025年1月6日周一 10:17写道： > > > > Hi,Christophe > > > > Christophe Leroy wrote on Saturday, 4 > > January 2025 03:58: > > > > > > > > > > > > Le 03/01/2025 à 11:51, Guo Weikang a écrit : > > > > After analyzing the usage of memblock_alloc, it was found that approximately > > > > 4/5 (120/155) of the calls expect a panic behavior on allocation failure. > > > > To reflect this common usage pattern, the default failure behavior of > > > > memblock_alloc is now modified to trigger a panic when allocation fails. > > > > > > > > Additionally, a new interface, memblock_alloc_no_panic, has been introduced > > > > to handle cases where panic behavior is not desired. > > > > > > Isn't that going in the opposite direction ? > > > > > > 5 years ago we did the exact reverse, see commit c0dbe825a9f1 > > > ("memblock: memblock_alloc_try_nid: don't panic") > > Thank you for providing the historical context. I did notice the > existence of a nopanic > version before. In my earlier patch, I introduced > memblock_alloc_or_panic, which offers > a more explicit interface to clearly indicate to callers that they > don't need to handle panic > separately. > > Andrew pointed out that in most scenarios, panic is the expected > behavior, while no_panic > represents an exceptional case. This feedback led to the current > patch, aiming to adjust the > default behavior and open it up for discussion within the community. > > However, after reviewing Mike's previous changes, I now believe that > further adjustment to > the default behavior might not be necessary, as it could lead to > confusion for many users. > In fact, the interface that is widely used externally is > memblock_alloc(), and I think providing memblock_alloc_or_panic > explicitly might already be sufficient. Agree > - memblock_alloc_or_panic: > https://lore.kernel.org/lkml/20250102150835.776fe72f565cc3232d83e6a7@linux-foundation.org/ > - Drop memblock_alloc_nopanic： > https://lore.kernel.org/lkml/1548057848-15136-1-git-send-email-rppt@linux.ibm.com/ > > > > > > > Christophe > > > > > > > -- Sincerely yours, Mike.