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Wed, 13 Dec 2023 07:28:27 GMT Received: from pps.reinject (localhost [127.0.0.1]) by iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 3uvep7tej6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 13 Dec 2023 07:28:27 +0000 Received: from iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 3BD7SRdv020500; Wed, 13 Dec 2023 07:28:27 GMT Received: from jfwang-mac.us.oracle.com (dhcp-10-159-129-184.vpn.oracle.com [10.159.129.184]) by iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTP id 3uvep7te97-1; Wed, 13 Dec 2023 07:28:27 +0000 From: Jianfeng Wang To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jianfeng Wang Subject: [PATCH] mm: remove redundant lru_add_drain() prior to unmapping pages Date: Tue, 12 Dec 2023 23:28:05 -0800 Message-ID: <20231213072805.74201-1-jianfeng.w.wang@oracle.com> X-Mailer: git-send-email 2.42.1 MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-12_14,2023-12-12_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 suspectscore=0 phishscore=0 malwarescore=0 spamscore=0 mlxlogscore=999 bulkscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2312130053 X-Proofpoint-ORIG-GUID: HraMxghePdLtKHJbsbQnLR9EzC-2LppB X-Proofpoint-GUID: HraMxghePdLtKHJbsbQnLR9EzC-2LppB X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 9F9B02000D X-Stat-Signature: bu68fr38tcnmtwaeq1okjjd37s76i7k8 X-HE-Tag: 1702452510-627853 X-HE-Meta: U2FsdGVkX1+df/6fcqjEhIjTOqrDxgu5cO96VwjKK7qQ8q+vDRIzZvmimr50GVeSbmRN2w4j1I5iz4Ub2ZSBPH7/KCO0xNUdq7HCQ8R+1hcUx83COzEKt5Sd4WsKmjLY5KtoEgdQN+px2Ir8sjCfqu6Cx1TVeHJQAKFfqlOia9Wdx/HydzSNTHDP9Tj+Hzz7wvKXhkWkQd8Pl4Rbs9OycbY2V+VOdVu+INtovzu0X4q5+q0tcYiQSQFB3d0BJ1SmVjisW2FwthM9W8YgfijKtkNJWlTIjvpj6qNziB8N0ya8SBHggMAvv2jsmsewHF1ZWTTgTtloqBzwTIwYxn78hDIPH5tI8lrp3RF7NbxqsW2SI+5ruKRy4wjWMa7QnW+lkvmq+Tm49CdPT4L2g87Enxt+ZPMTCwPhAi1/JkxkcIaPQO+TYHeZEuiY+eMq836BhgrIB9NZgkUmYMOMYGsDugDVMhIA8ZasPoGKzklPvttkorVBsWQP4I345Z16LdDv5Y6YPTY23gQ75IWHwxqsfZZpYMypt79Av59I9s0tDNK5dQs/Jd6z1BYd8imE2LwnQ1nCCwz4oFKCHd5I5HvXyhDr1EthnarOG9HzskO06T9ek3/UXeGWwkQytUaDG4vku+TjwZvgf5ebfPX8Ch3HOzgxpKupDiF31EVA6b7vbrtfF2K8ZxHcfN/lMH2dQAVP9Wb2X5QV9NphEmYpMpWfA4bxKkD6gc12wR4V7/uMEzFtqDWlW/tz4bq9CbKFqHJCiSU/qD8Gys/Vd1bk5olr6D9Xx2eYXhnrJDog7kl+w9IJHZlRBM5NN+aW9uKkOA+CLYFnI/xj5K9okiKv5jH27olwfFPUZwRkbGoL7VgwS7l81z14If4MLXIq7IqG4NJeyvMIgU2hX1Dgb+KcCLVWjciBmnblP2eO0KnBpAdAsiVqIc8chEKDTw1Gb4Q4liopkr/QgWb51MSIDcSdOgh tkrQJmoA Xfa9X7QGj1FtHrMth7qBqV2fg3WlN+HfUx2rhm43efEFkebNaPZduCYXJjV8JAk6EOx0/b0r98TpPSdNloWgyeU+W++hmj4+pbSu46DKpZEcfmZjTMenfyJbY69HiTy/zsUKbk2+jYyn5Evry4v4K8+WKFthjlx0Nxnw9nBLW02JNGdydL08I6ldGocRWqdwZui+u3HU9NynUX4OPxImYFNqV8nhxVprkvPSN4vVPvvVBuaBMZzQWnSvkqT2MmTBLERjI 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: When unmapping VMA pages, pages will be gathered in batch and released by tlb_finish_mmu() if CONFIG_MMU_GATHER_NO_GATHER is not set. The function tlb_finish_mmu() is responsible for calling free_pages_and_swap_cache(), which calls lru_add_drain() to drain cached pages in folio_batch before releasing gathered pages. Thus, it is redundant to call lru_add_drain() before gathering pages, if CONFIG_MMU_GATHER_NO_GATHER is not set. Remove lru_add_drain() prior to gathering and unmapping pages in exit_mmap() and unmap_region() if CONFIG_MMU_GATHER_NO_GATHER is not set. Note that the page unmapping process in oom_killer (e.g., in __oom_reap_task_mm()) also uses tlb_finish_mmu() and does not have redundant lru_add_drain(). So, this commit makes the code more consistent. Signed-off-by: Jianfeng Wang --- mm/mmap.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/mmap.c b/mm/mmap.c index 1971bfffcc03..0451285dee4f 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2330,7 +2330,9 @@ static void unmap_region(struct mm_struct *mm, struct ma_state *mas, struct mmu_gather tlb; unsigned long mt_start = mas->index; +#ifdef CONFIG_MMU_GATHER_NO_GATHER lru_add_drain(); +#endif tlb_gather_mmu(&tlb, mm); update_hiwater_rss(mm); unmap_vmas(&tlb, mas, vma, start, end, tree_end, mm_wr_locked); @@ -3300,7 +3302,9 @@ void exit_mmap(struct mm_struct *mm) return; } +#ifdef CONFIG_MMU_GATHER_NO_GATHER lru_add_drain(); +#endif flush_cache_mm(mm); tlb_gather_mmu_fullmm(&tlb, mm); /* update_hiwater_rss(mm) here? but nobody should be looking */