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From: Shakeel Butt To: zhongjinji Cc: mhocko@suse.com, rientjes@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, liam.howlett@oracle.com, lorenzo.stoakes@oracle.com, surenb@google.com, liulu.liu@honor.com, feng.han@honor.com, tianxiaobin@honor.com, fengbaopeng@honor.com Subject: Re: [PATCH v6 2/2] mm/oom_kill: The OOM reaper traverses the VMA maple tree in reverse order Message-ID: References: <20250829065550.29571-1-zhongjinji@honor.com> <20250829065550.29571-3-zhongjinji@honor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250829065550.29571-3-zhongjinji@honor.com> X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: ECB921A0008 X-Stat-Signature: jqig6k1h7fgqh8j5xgfqa89zwywfotpj X-HE-Tag: 1756509707-720312 X-HE-Meta: U2FsdGVkX19wNZPJWtgitnKb1HIxac2nTyPoujVjUBQ5mN0Qy8OCV2rvHLTJrcUSMl392GyqXm2C8Elfo6Qk25SGbm51QI4i2nsL/QkQSrUTwPQAYPrnmoMDbWahWtV5imATa8DY1m0zXOyjC+y2nTwY2FAw8HdU9pLIjobnHd4bi+7j9xuYFCh5u14FURSTTs/rsAB2CxF11Nysc8dHE1HSK1GZwTJjtxIDN4ieVw/3wYEEUgjUpkPXKje2NT+gPfzaM7/keyH4DYzBZibpRegFlMR0HsIUe9qUEhxicV0LGFspbjLw7EHs9A/NE7nSMdA+svCQ8mJQUP9b05nunwEVvNG1VyHOZWXsatnQVerviOoOyHuwCBWEt8ikZT+FavDhMKLC/KAGczZUFsOACrpoUXxs8guZRwmrholv9g9hTrQuXz7mgJ9KdA7X2yTxJfiX6N/4cptYPdHlIU1mxrZJUFmBGnCPWJ8zh41jNI/zlIrvw2EJXlInz1HTe7I1O8cz+A5mz24TZJ+pOuGExlxDqc3gA0hkxMSozoWSzTLNoQoV34ry+BuNAOGzhP84wyMXzCXaKUnHHWNw9iDm6uzrIJkrFzx5MN7kYyimlQhKYl4hKIXBLO2dn6aqdwXa/7q1Wfa7R1TAU2BqGKLJjjFHFF1Mh/ivR4cjOt7oNdsthp8RzCCG1S6XcQY5t/mXL+eNv0oQLCqNN01hjTWdfF4UHjrx444KSL6NFxL8K6uUjS6yC/123MFzZ+CfPJqQZwOsTJgqFVvVamkkp61nmcW0RUy56Mok/st9jGcIXNv7GJObNab3g0XwHEdC6/K5qSRQ8siK7eQJ7OJ/GM2YUniSJYg6PYWM9s4Tbop3dcY6LtxseymmWb5ubLQhr+7zoaCX6030I0O489QbPI2z5KX8FT5A7sA/akjIhSfPm9O1C9dmEINnkf6l3U2QLFD8bdnLbBn4/RtfWXOCiG4 TkY4kx8H 0TwVJXLXOHO/mXStgFrA1JqJ3B/B8UjUxPWW6HTn0sPT7SG8gjFtyWyuk+DaaHQ28nVE+yj81/am0W7HslQntb5X4MkbSUtZv44DLTNCZCrPsYqQg+A0OLWi1UUEK6p5Ygd7hJtR/afht5HNzA7YfTcZb+PQA1xYfJY2mn0G2Ijx1GzOzul+3WMnHM8FfqvIa3VD7pLMMI7sajT/vSHW/doqbYOKpovmB55PCKO85ovyrKBAlqm8uxhVnmctEnr8f6qJHtg1H5ytet2wfuQJnT9IELZTz5GS2745YvvegfYSifjAkFwbG46ZVBbTVg0wr954V2S+iavI9NCFSJLPC+Ec+S5m4LdEK5/nJ 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 Fri, Aug 29, 2025 at 02:55:50PM +0800, zhongjinji wrote: > When a process is OOM killed without reaper delay, the oom reaper and the > exit_mmap() thread likely run simultaneously. They traverse the vma's maple > tree along the same path and may easily unmap the same vma, causing them to > compete for the pte spinlock. > > When a process exits, exit_mmap() traverses the vma's maple tree from low > to high addresses. To reduce the chance of unmapping the same vma > simultaneously, the OOM reaper should traverse the vma's tree from high to > low address. > > Reported-by: tianxiaobin > Reported-by: fengbaopeng > > Signed-off-by: zhongjinji Acked-by: Shakeel Butt