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Wed, 06 Aug 2025 06:44:06 -0700 (PDT) From: Joshua Hahn To: "Huang, Ying" , Andrew Morton Cc: David Hildenbrand , SeongJae Park , Alistair Popple , Byungchul Park , Gregory Price , Matthew Brost , Rakie Kim , Zi Yan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-team@meta.com Subject: Re: [PATCH v3] mempolicy: Clarify what zone reclaim means Date: Wed, 6 Aug 2025 06:43:52 -0700 Message-ID: <20250806134404.2000234-1-joshua.hahnjy@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <87zfcduv3l.fsf@DESKTOP-5N7EMDA> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: CBE24160003 X-Rspam-User: X-Rspamd-Server: rspam09 X-Stat-Signature: miwhfizdaau6u55x75e1mc8f4ifx97en X-HE-Tag: 1754487847-962257 X-HE-Meta: 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 gOX8Ju95 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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 Wed, 06 Aug 2025 08:55:42 +0800 "Huang, Ying" wrote: > Joshua Hahn writes: > > > > /* > > + * Enabling zone reclaim means the page allocator will attempt to fulfill > > + * the allocation request on the current node by triggering reclaim and > > + * trying to shrink the current node. > > + * Fallback allocations on the next candidates in the zonelist are considered > > + * when reclaim fails to free up enough memory in the current node/zone. > > + * > > * These bit locations are exposed in the vm.zone_reclaim_mode sysctl > > - * ABI. New bits are OK, but existing bits can never change. > > + * ABI. New bits are OK, but existing bits should not be changed. > > Should we avoid to call sysctl ABI here? Hi Ying, Makes sense to me as well! Andrew -- I saw that you added this to mm-unstable yesterday, would you mind folding the small fixlet below in with it? Please let me know if you would rather that I send in a new version, whatever works best for you! As always, thank you for your help : -) Have a great day! Remove the reference to the vm.zone_reclaim_mode sysctl as an ABI. Signed-off-by: Joshua Hahn diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h index 683c130782f0..8fbbe613611a 100644 --- a/include/uapi/linux/mempolicy.h +++ b/include/uapi/linux/mempolicy.h @@ -72,8 +72,8 @@ enum { * Fallback allocations on the next candidates in the zonelist are considered * when reclaim fails to free up enough memory in the current node/zone. * - * These bit locations are exposed in the vm.zone_reclaim_mode sysctl - * ABI. New bits are OK, but existing bits should not be changed. + * These bit locations are exposed in the vm.zone_reclaim_mode sysctl. + * New bits are OK, but existing bits should not be changed. */ #define RECLAIM_ZONE (1<<0) /* Enable zone reclaim */ #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */