From mboxrd@z Thu Jan 1 00:00:00 1970 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 61090C433EF for ; Fri, 29 Apr 2022 06:40:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0F1376B007D; Fri, 29 Apr 2022 02:40:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 07F506B0078; Fri, 29 Apr 2022 02:40:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D24B36B0080; Fri, 29 Apr 2022 02:40:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.28]) by kanga.kvack.org (Postfix) with ESMTP id A4C3D6B0078 for ; Fri, 29 Apr 2022 02:40:37 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 8411121292 for ; Fri, 29 Apr 2022 06:40:37 +0000 (UTC) X-FDA: 79408968114.08.E65FF6D Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf04.hostedemail.com (Postfix) with ESMTP id C5F7F4007C for ; Fri, 29 Apr 2022 06:40:31 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.54]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KqNCR148kzhYrG; Fri, 29 Apr 2022 14:40:19 +0800 (CST) Received: from huawei.com (10.175.124.27) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 29 Apr 2022 14:40:34 +0800 From: Miaohe Lin To: , CC: , , Subject: [PATCH 7/9] mm/z3fold: always clear PAGE_CLAIMED under z3fold page lock Date: Fri, 29 Apr 2022 14:40:49 +0800 Message-ID: <20220429064051.61552-8-linmiaohe@huawei.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20220429064051.61552-1-linmiaohe@huawei.com> References: <20220429064051.61552-1-linmiaohe@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C5F7F4007C X-Stat-Signature: czqooxuchwsqh1xrri45j4z6deptgska X-Rspam-User: Authentication-Results: imf04.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf04.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-HE-Tag: 1651214431-846461 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: Think about the below race window: CPU1 CPU2 z3fold_reclaim_page z3fold_free test_and_set_bit PAGE_CLAIMED failed to reclaim page z3fold_page_lock(zhdr); add back to the lru list; z3fold_page_unlock(zhdr); get_z3fold_header page_claimed=test_and_set_bit PAGE_CLAIMED clear_bit(PAGE_CLAIMED, &page->private); if (!page_claimed) /* it's false true */ free_handle is not called free_handle won't be called in this case. So z3fold_buddy_slots will leak. Fix it by always clear PAGE_CLAIMED under z3fold page lock. Signed-off-by: Miaohe Lin --- mm/z3fold.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/z3fold.c b/mm/z3fold.c index a1c150fc8def..4a3cd2ff15b0 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -1221,8 +1221,8 @@ static void z3fold_free(struct z3fold_pool *pool, unsigned long handle) return; } if (test_and_set_bit(NEEDS_COMPACTING, &page->private)) { - put_z3fold_header(zhdr); clear_bit(PAGE_CLAIMED, &page->private); + put_z3fold_header(zhdr); return; } if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) { @@ -1424,8 +1424,8 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries) spin_unlock(&pool->lock); if (list_empty(&zhdr->buddy)) add_to_unbuddied(pool, zhdr); - z3fold_page_unlock(zhdr); clear_bit(PAGE_CLAIMED, &page->private); + z3fold_page_unlock(zhdr); } /* We started off locked to we need to lock the pool back */ @@ -1577,8 +1577,8 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa if (!z3fold_page_trylock(zhdr)) return -EAGAIN; if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0) { - z3fold_page_unlock(zhdr); clear_bit(PAGE_CLAIMED, &page->private); + z3fold_page_unlock(zhdr); return -EBUSY; } if (work_pending(&zhdr->work)) { -- 2.23.0