From patchwork Thu Oct 31 22:16:02 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Weiner X-Patchwork-Id: 11221951 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E79A8913 for ; Thu, 31 Oct 2019 22:16:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A91062086D for ; Thu, 31 Oct 2019 22:16:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="IDDK+UpM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A91062086D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=cmpxchg.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CC0D86B0005; Thu, 31 Oct 2019 18:16:06 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id C714F6B0006; Thu, 31 Oct 2019 18:16:06 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B38F06B0007; Thu, 31 Oct 2019 18:16:06 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 8CF816B0005 for ; Thu, 31 Oct 2019 18:16:06 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id C6F2687F1 for ; Thu, 31 Oct 2019 22:16:05 +0000 (UTC) X-FDA: 76105488690.14.maid97_180c65238d559 X-Spam-Summary: 2,0,0,4fe86f366ea89fb9,d41d8cd98f00b204,hannes@cmpxchg.org,:akpm@linux-foundation.org::linux-kernel@vger.kernel.org:kernel-team@fb.com,RULES_HIT:41:355:379:541:800:960:973:988:989:1260:1311:1314:1345:1437:1515:1534:1539:1711:1714:1730:1747:1777:1792:2198:2199:2393:2559:2562:3138:3139:3140:3141:3142:3351:3622:3865:3866:3868:3871:3872:4321:5007:6261:6653:10004:11026:11658:11914:12296:12297:12438:12517:12519:12555:12895:12986:13069:13311:13357:13894:14181:14384:14394:14721:21080:21444:21451:21627:30054,0,RBL:209.85.160.194:@cmpxchg.org:.lbl8.mailshell.net-62.2.0.100 66.100.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:24,LUA_SUMMARY:none X-HE-Tag: maid97_180c65238d559 X-Filterd-Recvd-Size: 3527 Received: from mail-qt1-f194.google.com (mail-qt1-f194.google.com [209.85.160.194]) by imf36.hostedemail.com (Postfix) with ESMTP for ; Thu, 31 Oct 2019 22:16:05 +0000 (UTC) Received: by mail-qt1-f194.google.com with SMTP id y10so3852607qto.3 for ; Thu, 31 Oct 2019 15:16:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=rvzKkNDnFw8WgEsEEsv1HzkDI4bs5dlMd1q1SJlSRv8=; b=IDDK+UpMUsRWxn79to0tss/Udaa2EnOB3HfpzeuN+sK1qCRI5FyV/QzNzsS7OOr9+w uexitjcUSu0EToVQtruGvGYqrTR3Zb8B6WiuY/oo5A4TeAEwktQqtNARmn+yIH0G91km oY7J0NjnqjXoh0wGiX0SOOS0uzfMuCztFNMqXuPNw1JhqDcS/b2ufzSuUMZP4GZIf6ot QwGxWRb5o9XIekockwk6hdk/UxsQw18QyS37rDT3xWJSGLm5WH8hCVqEkqpW5L24+P5i wDzYtit4hSwUHd07pXrCCjkerLSZbVegytzILb2WJM48locQzG/1EwyYMDqL9T/E7o8W c1RQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=rvzKkNDnFw8WgEsEEsv1HzkDI4bs5dlMd1q1SJlSRv8=; b=SkRD2EiOxqZ6w7VvhjpqJpKSI0xzgRIOulg/xahd4cFOowxB+byecyM0i/q4OicEbg ZVa9hJnGWxKzDYi6q9jGZoEc5EHrdfsd/40mYDV55f5LS6yBswG+7oEELM/U+oB9T4lX /ulj+iRn7AGUPPt33HvwAJxUtyRtwbtR39v7kj2hYXxPSVmzhuWNCanwZbnbi5NP+IuA Y1dSgeOeLZtUKixuE9E7YP7Nb+JihLGP94+BpfFt9xMCQBvs1p7OcA9MRl8CW4m+gWbT XEd1vDUvrS7yV6nSLzAmdBP1hcOlO0r5n6jaRS/yPqOkRn2fKamRAPqah8nkkui3iEvq o6SQ== X-Gm-Message-State: APjAAAXIlWAlcIIRI/UeqFnr0w5sCiYdQEGvEitgJOLTi413YzHRdpX5 D1GOP92YPF9+dbvIdQKm2NWnQw== X-Google-Smtp-Source: APXvYqyUuLqB0cI+w53Vd93MAjEXiqViJpN4Vahcb11eeMP6ArsUp/aFprEaAG5BZjXBK3yNn7GvDQ== X-Received: by 2002:ac8:866:: with SMTP id x35mr7645846qth.90.1572560164030; Thu, 31 Oct 2019 15:16:04 -0700 (PDT) Received: from localhost ([2620:10d:c091:500::c357]) by smtp.gmail.com with ESMTPSA id x12sm2151101qkh.96.2019.10.31.15.16.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 31 Oct 2019 15:16:03 -0700 (PDT) From: Johannes Weiner To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH] kernel: sysctl: make drop_caches write-only Date: Thu, 31 Oct 2019 18:16:02 -0400 Message-Id: <20191031221602.9375-1-hannes@cmpxchg.org> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 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: Currently, the drop_caches proc file and sysctl read back the last value written, suggesting this is somehow a stateful setting instead of a one-time command. Make it write-only, like e.g. compact_memory. Signed-off-by: Johannes Weiner Acked-by: Chris Down Acked-by: David Hildenbrand Acked-by: Vlastimil Babka Acked-by: Michal Hocko --- kernel/sysctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 31ece1120aa4..50373984a5e2 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1474,7 +1474,7 @@ static struct ctl_table vm_table[] = { .procname = "drop_caches", .data = &sysctl_drop_caches, .maxlen = sizeof(int), - .mode = 0644, + .mode = 0200, .proc_handler = drop_caches_sysctl_handler, .extra1 = SYSCTL_ONE, .extra2 = &four,