From patchwork Tue Aug 2 01:32:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: mawupeng X-Patchwork-Id: 12934191 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 67AD1C00144 for ; Tue, 2 Aug 2022 01:33:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EFC426B0071; Mon, 1 Aug 2022 21:33:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EAC8D6B0072; Mon, 1 Aug 2022 21:33:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D99C68E0001; Mon, 1 Aug 2022 21:33:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id CC47C6B0071 for ; Mon, 1 Aug 2022 21:33:21 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 9D61D40CA9 for ; Tue, 2 Aug 2022 01:33:21 +0000 (UTC) X-FDA: 79752929802.16.42BEACD Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by imf18.hostedemail.com (Postfix) with ESMTP id BC5961C0108 for ; Tue, 2 Aug 2022 01:33:20 +0000 (UTC) Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Lxcpj4d2SzWf48; Tue, 2 Aug 2022 09:29:17 +0800 (CST) Received: from dggpemm500014.china.huawei.com (7.185.36.153) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 2 Aug 2022 09:33:16 +0800 Received: from localhost.localdomain (10.175.112.125) by dggpemm500014.china.huawei.com (7.185.36.153) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 2 Aug 2022 09:33:15 +0800 From: Wupeng Ma To: , , , CC: , , , , Subject: [PATCH stable 4.14,4.19 1/1] mm: Fix page counter mismatch in shmem_mfill_atomic_pte Date: Tue, 2 Aug 2022 09:32:51 +0800 Message-ID: <20220802013251.3022141-1-mawupeng1@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.175.112.125] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500014.china.huawei.com (7.185.36.153) X-CFilter-Loop: Reflected ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659404001; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding:in-reply-to: references; bh=ZJS/Ii27WTKTvLmJ3XL7hwYd0OGjg/66Tb8WKH28cfg=; b=2JEKRAftkirdvEeCq5fHflfzYuy8ovqYd916u34BSnyiOJyeV9nqxlrkHvTMxYYCA1BU77 RuY6oYrbIGMNVQ4QXu4Cr47XRsoMLx7fOmv0CwRi4yacqOwUoffgdy9tTaIM3AkYtT7OVz XN1mquxU1kdMETgqTMI9a0KxJMRpxJ8= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=none; spf=pass (imf18.hostedemail.com: domain of mawupeng1@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=mawupeng1@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659404001; a=rsa-sha256; cv=none; b=KSy0KzLIvOG/KCwUIMOjO8FPrF1viPM73c9vTK48stsEvHGh06NiBl6ObGf8vAof2s6wJ1 Z+kOuOs+nQImpdIJOd1c9aqrILBD65O50zui5UP0inRCUYRrsM6wgAuyqAWcuBBXMRgnaf WR5IymRd7ZLN0mogaT7BafleYZV4h5E= Authentication-Results: imf18.hostedemail.com; dkim=none; spf=pass (imf18.hostedemail.com: domain of mawupeng1@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=mawupeng1@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: BC5961C0108 X-Stat-Signature: st53c75m8cnwigieh55g4nn4soq3ibcw X-HE-Tag: 1659404000-311062 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: From: Ma Wupeng shmem_mfill_atomic_pte() wrongly called mem_cgroup_cancel_charge() in "success" path, it should mem_cgroup_uncharge() to dec memory counter instead. mem_cgroup_cancel_charge() should only be used if this transaction is unsuccessful and mem_cgroup_uncharge() is used to do this if this transaction succeed. This will lead to page->memcg not null and will uncharge one more in put_page(). The page counter will underflow to maximum value and trigger oom to kill all process include sshd and leave system unaccessible. page->memcg is set in the following path: mem_cgroup_commit_charge commit_charge page->mem_cgroup = memcg; extra uncharge will be done in the following path: put_page __put_page __put_single_page mem_cgroup_uncharge if (!page->mem_cgroup) <-- should return here return uncharge_page uncharge_batch To fix this, call mem_cgroup_commit_charge() at the end of this transaction to make sure this transaction is really finished. Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Ma Wupeng --- mm/shmem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 0788616696dc..0b06724c189e 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2339,8 +2339,6 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (ret) goto out_release_uncharge; - mem_cgroup_commit_charge(page, memcg, false, false); - _dst_pte = mk_pte(page, dst_vma->vm_page_prot); if (dst_vma->vm_flags & VM_WRITE) _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte)); @@ -2366,6 +2364,8 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (!pte_none(*dst_pte)) goto out_release_uncharge_unlock; + mem_cgroup_commit_charge(page, memcg, false, false); + lru_cache_add_anon(page); spin_lock_irq(&info->lock);