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a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1689357263; bh=fdVkW64IxxcF8DxXW9FKwBOs41Z3K3ZO+58rMAhgv6Y=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=t3yNB4qUTKucGZQRMmAXccb95B8Olhm45qBpLUz1VrWdfUHo1tjZCy4i9zXgjnWpC 1vhw2g687TfMz+I9p2nejpK51vcLdPW+gLHJJLWAD2K9o+TGXmn1TJlwGA1gWZ+SZV Ey/qB0hHRQTn+ERdMEB/mLRBzhXmJCK0DQFC+BjA= Date: Fri, 14 Jul 2023 10:54:22 -0700 From: Andrew Morton To: Kemeng Shi Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] mm/page_ext: remove rollback for untouched mem_section in online_page_ext Message-Id: <20230714105422.648d17f9ba6141f26e469423@linux-foundation.org> In-Reply-To: <20230714114749.1743032-3-shikemeng@huaweicloud.com> References: <20230714114749.1743032-1-shikemeng@huaweicloud.com> <20230714114749.1743032-3-shikemeng@huaweicloud.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 35DA210001D X-Stat-Signature: 4wfbkfxi7bm69iuukhjgtx94oiuudpz8 X-HE-Tag: 1689357264-353509 X-HE-Meta: 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 BSizfxaP oP0MNESne84LfIRzpBcomM0oCl9PfsgoCt29HqxzKCaumNJ+H78UJ3PholWIKtN8wF9reYNDfODY5CJ1eXIt1I6JCzSI7033Eo27rL4jXvXWaAKVmsC+vpmyNflHENW+Mmi+XIb4KHlic+H7bnrQQ7nLb+k66d4J8ihCWdrcqA01mdAiebYSgilXtNtd5TqHWegy3wfUKeLC/FhOArMKZ+3NJfkBfda7knM5TCpJTFNCZsR3TJtVbvGdthaWsJ3Ojy15opLhZsnKpm0VG1+N+WElGMWdUJL/0INEDeHDwQUHT3NTwCW9IEbLqwUWqQw6shT/gcMRAjpfVLKuVSsZ4yUVqPOo3zvHJXGAabj6EIl2xZaUdH8eMI1hMGN82x1hm6DSgnmLko3h8lnU6niMIoqgA8K6ELSn/AZU3f3cHJYBrFnJKUzgTXccZWA== 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 Fri, 14 Jul 2023 19:47:48 +0800 Kemeng Shi wrote: > If init_section_page_ext failed, we only need rollback for mem_section > before failed mem_section. Make rollback end point to failed mem_section > to remove unnecessary rollback. > > As pfn += PAGES_PER_SECTION will be executed even if init_section_page_ext > failed. So pfn points to mem_section after failed mem_section. Subtract > one mem_section from pfn to get failed mem_section. > > ... > > --- a/mm/page_ext.c > +++ b/mm/page_ext.c > @@ -424,6 +424,7 @@ static int __meminit online_page_ext(unsigned long start_pfn, > return 0; > > /* rollback */ > + end = pfn - PAGES_PER_SECTION; > for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) > __free_page_ext(pfn); > This is a bugfix, yes? I guess init_section_page_ext() never fails for anyone...