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[209.85.220.73]) by mx.google.com with SMTPS id k186sor3016390qkc.108.2019.05.04.07.52.50 for (Google Transport Security); Sat, 04 May 2019 07:52:51 -0700 (PDT) Received-SPF: pass (google.com: domain of 3qqfnxagkclmlatdxxeuzhhzex.vhfebgnq-ffdotvd.hkz@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=qFtjqSrc; spf=pass (google.com: domain of 3qqfnxagkclmlatdxxeuzhhzex.vhfebgnq-ffdotvd.hkz@flex--shakeelb.bounces.google.com designates 209.85.220.73 as permitted sender) smtp.mailfrom=3QqfNXAgKCLMlaTdXXeUZhhZeX.Vhfebgnq-ffdoTVd.hkZ@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:message-id:mime-version:subject:from:to:cc; bh=Q+yvnmyjVEzdFHEWBcoadDmmU/3yK5ganIOIoyEwouc=; b=qFtjqSrcM4UGgRoJ8/RzfeaVyMan+d7Ts2pByis/59NTZYLaxr1drG0H5BJleMrsrh MfXyUTFpANjtUv9d/3lln9gmv0JiZwKgSmPn/unKXf6ckvtwaiukK2EpBgYXSp2zaMVT oBZSmqvUFGBLW+493GEBswqRKrbAhreW7h3pvJZKJyvSY9xqc6PSChOyIBpwKVl7OcOV OYC8eGUnH5wq7H0Hf6xM8doNcgTcKdvF+OGgfSn2qK2KmkPDC1b9x7Pj9K9UegrblR69 dmm+H2DsQQ2Abc1ZsllHD5tiuI6keEcXuEUtH1k4JAzFM/AERoSNSFeerIz2sPD+jA9M 2gsA== X-Google-Smtp-Source: APXvYqzaEcIiqQDURcZKk/Ciux9eOBC26QDYKJQb+X0sd9obaCdABR9WDozc3I83/n6peCeKM9N158e14DQdFQ== X-Received: by 2002:a05:620a:1015:: with SMTP id z21mr3134470qkj.229.1556981570541; Sat, 04 May 2019 07:52:50 -0700 (PDT) Date: Sat, 4 May 2019 07:52:42 -0700 Message-Id: <20190504145242.258875-1-shakeelb@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog Subject: [PATCH v2] 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 v1: - Fixed usage of __GFP_RETRY_MAYFAIL flag. fs/notify/fanotify/fanotify.c | 5 ++++- fs/notify/inotify/inotify_fsnotify.c | 7 +++++-- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 6b9c27548997..f78fd4c8f12d 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. Also make sure to not trigger OOM killer in the + * target memcg for the limited size queues. */ 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..17c08daa1ba7 100644 --- a/fs/notify/inotify/inotify_fsnotify.c +++ b/fs/notify/inotify/inotify_fsnotify.c @@ -99,9 +99,12 @@ 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. However + * do not trigger the OOM killer in the target memcg. + */ 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)) {