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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB7C7C433F5 for ; Thu, 19 May 2022 07:14:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231523AbiESHOd (ORCPT ); Thu, 19 May 2022 03:14:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229548AbiESHOb (ORCPT ); Thu, 19 May 2022 03:14:31 -0400 Received: from mail-yw1-x112b.google.com (mail-yw1-x112b.google.com [IPv6:2607:f8b0:4864:20::112b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 451E563F0 for ; Thu, 19 May 2022 00:14:30 -0700 (PDT) Received: by mail-yw1-x112b.google.com with SMTP id 00721157ae682-2ec42eae76bso47492497b3.10 for ; Thu, 19 May 2022 00:14:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=konsulko.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=m4dkMUBjXmr29DvEu0d7QY2KaK3h+KI8JPQ8UIjV1nc=; b=ncHRyuryZDkR9T6KwBhdvmfTdnAe4BGbnp+zbgHgPV0y8KTH3fZACSGswVkNnuJNSO +cWvux3fhUOd+fQHIWJn1GlH3AkcQPDPHrylAV31iuD0QPxQwPV5E+wze30wY8Dd9/Bz jei+9+6NmzwObudOZpdcZ9+CK3gkUJ7EO4Arc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=m4dkMUBjXmr29DvEu0d7QY2KaK3h+KI8JPQ8UIjV1nc=; b=DlH6Q+s5oFd59MGzVGppjzRnG51LyWLo6Ak1KL5R6ea9+h3qDaXVs16QrEWF9MZS1R Krj0T70H9+95xk3BKz3c1qL76T50ksCMi8uCRoY5Ybxw2EoJpgSar1uPQevIqjrsCJFr k3dMzlpR43HKnd1PDC8IWmFbMPCXMJ4Kc6AaKzBf1/O2aXS30fgpNeFPZRzGwf/fs1TY 9AYe719cNPknbmel1zmce20sZvIa7zEbPasLZlg6r2CL4wq5hW9dfVBbz1Rz6a25BKq9 nYCOLRkoRRL0LOMWfgTzJ9gt6Arw4CgT0Sz2OsE3jmfUQjNrQlJj4SjEXV+CX3R879kS ONiQ== X-Gm-Message-State: AOAM532R54fx5bOhW95yk+wsZXh5VMDZhjkmhTNpZgtX+dkZso+H3QDl 64I8/oYt8kN9izLaI0CnNdGRG4PBykH9FV8v8lD+uw== X-Google-Smtp-Source: ABdhPJwHCiCtOihK3wf0xQOM/tNKltnbYn/XzVurFQjmOkO9x7QCVrZKymk7KwDLe0/jLMrgd2fiZVlaLJi43mFdlc4= X-Received: by 2002:a0d:ca82:0:b0:2ff:4451:7591 with SMTP id m124-20020a0dca82000000b002ff44517591mr3209343ywd.352.1652944469482; Thu, 19 May 2022 00:14:29 -0700 (PDT) MIME-Version: 1.0 References: <20220429064051.61552-1-linmiaohe@huawei.com> <20220429064051.61552-8-linmiaohe@huawei.com> In-Reply-To: <20220429064051.61552-8-linmiaohe@huawei.com> From: Vitaly Wool Date: Thu, 19 May 2022 09:14:18 +0200 Message-ID: Subject: Re: [PATCH 7/9] mm/z3fold: always clear PAGE_CLAIMED under z3fold page lock To: Miaohe Lin Cc: Andrew Morton , Linux-MM , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 29, 2022 at 8:40 AM Miaohe Lin wrote: > > 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)) { Reviewed-by: Vitaly Wool > -- > 2.23.0 >