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[209.85.220.73]) by mx.google.com with SMTPS id r17sor8770512otg.84.2019.05.14.14.23.23 for (Google Transport Security); Tue, 14 May 2019 14:23:23 -0700 (PDT) Received-SPF: pass (google.com: domain of 3yzhbxagkcig4tmwqqxns00sxq.o0yxuz69-yyw7mow.03s@flex--shakeelb.bounces.google.com designates 209.85.220.73 as permitted sender) client-ip=209.85.220.73; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=sMT1RFNI; spf=pass (google.com: domain of 3yzhbxagkcig4tmwqqxns00sxq.o0yxuz69-yyw7mow.03s@flex--shakeelb.bounces.google.com designates 209.85.220.73 as permitted sender) smtp.mailfrom=3yzHbXAgKCIg4tmwqqxns00sxq.o0yxuz69-yyw7mow.03s@flex--shakeelb.bounces.google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=/OYdIOpBJWCaBVUA2Ic/FHOWBWsqkzG28ElRwkV1PdY=; b=sMT1RFNIRx5Pslx1X+QRbggc6ZXdETqqUAmpYgQSfraDuAQ8m+rCMJk9uGbN6XrtHs tNkvdtsnGfHoH0GanvDXD+Fs6bm/IXQXFezj+d5P3ki8zYgnqAS/EoN5nDZJYNmbLDDZ AD+gARqdfYcjkA8KcwkxfSVO5a9PAtkxFAxt3FbP4bS2eGGNq3CxcOuewuBwbiFTdBqU r7UgPx4uwRpQE1MDB1pPgHNp+1PjjD8hA3bPI3U9YQ0+0oF6F4BpTGINJsrUutnPzVQ4 YwgfaJcSrkTC6Jzttdasq2d0xMgnfgYbpVVOKTamjEKDeaSR84z3dR/se+nCH6uaSBCN i3MA== X-Google-Smtp-Source: APXvYqym1Fqm5pNm2/VExHxbmxANidF+rxgp75ZamTBrHNj9XD2E4iXLCfQcbSoRxPswid69DBp+ecjJ3EluAg== X-Received: by 2002:a9d:5f13:: with SMTP id f19mr121436oti.219.1557869003332; Tue, 14 May 2019 14:23:23 -0700 (PDT) Date: Tue, 14 May 2019 14:22:59 -0700 In-Reply-To: <20190514212259.156585-1-shakeelb@google.com> Message-Id: <20190514212259.156585-2-shakeelb@google.com> Mime-Version: 1.0 References: <20190514212259.156585-1-shakeelb@google.com> X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog Subject: [PATCH v3 2/2] memcg, fsnotify: no oom-kill for remote memcg charging From: Shakeel Butt To: Johannes Weiner , Vladimir Davydov , Michal Hocko , Andrew Morton , Roman Gushchin , Jan Kara , Amir Goldstein Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Shakeel Butt 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 The commit d46eb14b735b ("fs: fsnotify: account fsnotify metadata to kmemcg") added remote memcg charging for fanotify and inotify event objects. The aim was to charge the memory to the listener who is interested in the events but without triggering the OOM killer. Otherwise there would be security concerns for the listener. At the time, oom-kill trigger was not in the charging path. A parallel work added the oom-kill back to charging path i.e. commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the charge path"). So to not trigger oom-killer in the remote memcg, explicitly add __GFP_RETRY_MAYFAIL to the fanotigy and inotify event allocations. Signed-off-by: Shakeel Butt Reviewed-by: Roman Gushchin --- Changelog since v2: - updated the comments. Changelog since v1: - Fixed usage of __GFP_RETRY_MAYFAIL flag. fs/notify/fanotify/fanotify.c | 5 ++++- fs/notify/inotify/inotify_fsnotify.c | 8 ++++++-- 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 6b9c27548997..8047d2fd4f27 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -288,10 +288,13 @@ struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, /* * For queues with unlimited length lost events are not expected and * can possibly have security implications. Avoid losing events when - * memory is short. + * memory is short. For the limited size queues, avoid OOM killer in the + * target monitoring memcg as it may have security repercussion. */ if (group->max_events == UINT_MAX) gfp |= __GFP_NOFAIL; + else + gfp |= __GFP_RETRY_MAYFAIL; /* Whoever is interested in the event, pays for the allocation. */ memalloc_use_memcg(group->memcg); diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c index ff30abd6a49b..ca1a9dfff0b5 100644 --- a/fs/notify/inotify/inotify_fsnotify.c +++ b/fs/notify/inotify/inotify_fsnotify.c @@ -99,9 +99,13 @@ int inotify_handle_event(struct fsnotify_group *group, i_mark = container_of(inode_mark, struct inotify_inode_mark, fsn_mark); - /* Whoever is interested in the event, pays for the allocation. */ + /* + * Whoever is interested in the event, pays for the allocation. Do not + * trigger OOM killer in the target monitoring memcg as it may have + * security repercussion. + */ memalloc_use_memcg(group->memcg); - event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT); + event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL); memalloc_unuse_memcg(); if (unlikely(!event)) {