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[156.151.31.86]) by mx.google.com with ESMTPS id b192si5735518qkc.367.2019.07.12.10.50.46 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 12 Jul 2019 10:50:46 -0700 (PDT) Received-SPF: pass (google.com: domain of darrick.wong@oracle.com designates 156.151.31.86 as permitted sender) client-ip=156.151.31.86; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2018-07-02 header.b=WmIBn4Tz; spf=pass (google.com: domain of darrick.wong@oracle.com designates 156.151.31.86 as permitted sender) smtp.mailfrom=darrick.wong@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x6CHj40F087152; Fri, 12 Jul 2019 17:50:43 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=x7UvLQTSUB1LsR4hNhBIrs6gKfi4eqgBS41bGNCZxkE=; b=WmIBn4TzVxJx7tITkiSdrxbMpLlvOyowIFmWIQLvD8rTXOemFcj/0peG8zV3LJOZopYV 5hKdk0m359lkfQ7nMT4n2GhVSOCH4wp95EOwzR6Ohrzx9y5528wIXvddyfPrfkytsJDI SNvy/mobFyaDD+GB0eg8nzsY+gbUx03fqPfGr0UgLAx4VLkrQkety9jgD4AAHLwrZpa6 HYfIZYhjoI1JkxBBH4sfGEdHz/pHZJjw/NmTv1sSRBHGcdIShUvN18StFkQ7qAZJKrpq 5qdQ9L3z/Q/UdLLt6fdxQ9dJx6oa3hNyB6f6Us/sRV1+OoU5AKQpKtclrhQZES7W/CVA wg== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2130.oracle.com with ESMTP id 2tjk2u71re-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 12 Jul 2019 17:50:43 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x6CHlfJb072667; Fri, 12 Jul 2019 17:50:43 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3030.oracle.com with ESMTP id 2tn1j296kb-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 12 Jul 2019 17:50:43 +0000 Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x6CHofoJ017303; Fri, 12 Jul 2019 17:50:41 GMT Received: from localhost (/10.159.245.178) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 12 Jul 2019 10:50:41 -0700 Date: Fri, 12 Jul 2019 10:50:40 -0700 From: "Darrick J. Wong" To: Jan Kara Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, Amir Goldstein , Boaz Harrosh , stable@vger.kernel.org Subject: Re: [PATCH 1/3] mm: Handle MADV_WILLNEED through vfs_fadvise() Message-ID: <20190712175040.GY1404256@magnolia> References: <20190711140012.1671-1-jack@suse.cz> <20190711140012.1671-2-jack@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190711140012.1671-2-jack@suse.cz> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9316 signatures=668688 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907120180 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9316 signatures=668688 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907120180 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: On Thu, Jul 11, 2019 at 04:00:10PM +0200, Jan Kara wrote: > Currently handling of MADV_WILLNEED hint calls directly into readahead > code. Handle it by calling vfs_fadvise() instead so that filesystem can > use its ->fadvise() callback to acquire necessary locks or otherwise > prepare for the request. > > Suggested-by: Amir Goldstein > CC: stable@vger.kernel.org # Needed by "xfs: Fix stale data exposure > when readahead races with hole punch" > Signed-off-by: Jan Kara Looks reasonable to me, though is this race between readahead and truncate severe enough to try to push it as a fix for 5.3 or are you targetting 5.4? --D > --- > mm/madvise.c | 22 ++++++++++++++++------ > 1 file changed, 16 insertions(+), 6 deletions(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 628022e674a7..ae56d0ef337d 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -14,6 +14,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -275,6 +276,7 @@ static long madvise_willneed(struct vm_area_struct *vma, > unsigned long start, unsigned long end) > { > struct file *file = vma->vm_file; > + loff_t offset; > > *prev = vma; > #ifdef CONFIG_SWAP > @@ -298,12 +300,20 @@ static long madvise_willneed(struct vm_area_struct *vma, > return 0; > } > > - start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; > - if (end > vma->vm_end) > - end = vma->vm_end; > - end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; > - > - force_page_cache_readahead(file->f_mapping, file, start, end - start); > + /* > + * Filesystem's fadvise may need to take various locks. We need to > + * explicitly grab a reference because the vma (and hence the > + * vma's reference to the file) can go away as soon as we drop > + * mmap_sem. > + */ > + *prev = NULL; /* tell sys_madvise we drop mmap_sem */ > + get_file(file); > + up_read(¤t->mm->mmap_sem); > + offset = (loff_t)(start - vma->vm_start) > + + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); > + vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED); > + fput(file); > + down_read(¤t->mm->mmap_sem); > return 0; > } > > -- > 2.16.4 >