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[192.55.52.93]) by mx.google.com with ESMTPS id z13-v6si5131001pfc.118.2018.08.03.04.25.04 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 03 Aug 2018 04:25:04 -0700 (PDT) Received-SPF: pass (google.com: domain of wei.w.wang@intel.com designates 192.55.52.93 as permitted sender) client-ip=192.55.52.93; Authentication-Results: mx.google.com; spf=pass (google.com: domain of wei.w.wang@intel.com designates 192.55.52.93 as permitted sender) smtp.mailfrom=wei.w.wang@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 03 Aug 2018 04:25:04 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,438,1526367600"; d="scan'208";a="62107286" Received: from devel-ww.sh.intel.com ([10.239.48.110]) by orsmga008.jf.intel.com with ESMTP; 03 Aug 2018 04:25:02 -0700 From: Wei Wang To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, akpm@linux-foundation.org, penguin-kernel@I-love.SAKURA.ne.jp, chris@chris-wilson.co.uk, mst@redhat.com Cc: wei.w.wang@intel.com Subject: [PATCH] mm/vmscan: adjust shrinkctl->nr_scanned after invoking scan_objects Date: Fri, 3 Aug 2018 18:56:49 +0800 Message-Id: <1533293809-34354-1-git-send-email-wei.w.wang@intel.com> X-Mailer: git-send-email 2.7.4 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: X-Virus-Scanned: ClamAV using ClamSMTP Some shrinkers may free more than the requested nr_to_scan of pages in one invocation of scan_objects, and some may free less than that. Currently shrinkers can either return the actual number of pages that have been freed via the return value of scan_objects or track that actual number in shrinkctl->nr_scanned. But do_shrink_slab works on an assumption that the actual number is always tracked via shrinkctl->nr_scanned, which is not true. Having checked the shrinkers used in the kernel, they basically return the actual number of freed pages via the return value of scan_objects, and most of them leave shrinkctl->nr_scanned unchanged after scan_objects is called. So this patch adjusts shrinkctl->nr_scanned to the actual freed number after scan_objects is called. Signed-off-by: Wei Wang Cc: Michal Hocko Cc: Andrew Morton Cc: Tetsuo Handa Cc: Chris Wilson Cc: Michael S. Tsirkin --- mm/vmscan.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 03822f8..78a75b9 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -447,9 +447,13 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, if (ret == SHRINK_STOP) break; freed += ret; + shrinkctl->nr_scanned = ret; count_vm_events(SLABS_SCANNED, shrinkctl->nr_scanned); - total_scan -= shrinkctl->nr_scanned; + if (total_scan > shrinkctl->nr_scanned) + total_scan -= shrinkctl->nr_scanned; + else + total_scan = 0; scanned += shrinkctl->nr_scanned; cond_resched();