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From: Christoph Hellwig <hch@infradead.org>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
	Christoph Hellwig <hch@infradead.org>,
	"Darrick J. Wong" <djwong@kernel.org>, Ted Tso <tytso@mit.edu>,
	Dave Chinner <david@fromorbit.com>,
	Matthew Wilcox <willy@infradead.org>,
	linux-mm@kvack.org, linux-xfs@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 03/14] mm: Protect operations adding pages to page cache with invalidate_lock
Date: Tue, 13 Jul 2021 07:25:05 +0100	[thread overview]
Message-ID: <YO0xwY+q7d8rQE3f@infradead.org> (raw)
In-Reply-To: <20210712165609.13215-3-jack@suse.cz>

Still looks good.  That being said the additional conditional locking in
filemap_fault makes it fall over the readbility cliff for me.  Something
like this on top of your series would help:

diff --git a/mm/filemap.c b/mm/filemap.c
index fd3f94d36c49..0fad08331cf4 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3040,21 +3040,23 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 	 * Do we have something in the page cache already?
 	 */
 	page = find_get_page(mapping, offset);
-	if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
+	if (likely(page)) {
 		/*
-		 * We found the page, so try async readahead before
-		 * waiting for the lock.
+		 * We found the page, so try async readahead before waiting for
+		 * the lock.
 		 */
-		fpin = do_async_mmap_readahead(vmf, page);
-	} else if (!page) {
+		if (!(vmf->flags & FAULT_FLAG_TRIED))
+			fpin = do_async_mmap_readahead(vmf, page);
+		if (unlikely(!PageUptodate(page))) {
+			filemap_invalidate_lock_shared(mapping);
+			mapping_locked = true;
+		}
+	} else {
 		/* No page in the page cache at all */
 		count_vm_event(PGMAJFAULT);
 		count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
 		ret = VM_FAULT_MAJOR;
 		fpin = do_sync_mmap_readahead(vmf);
-	}
-
-	if (!page) {
 retry_find:
 		/*
 		 * See comment in filemap_create_page() why we need
@@ -3073,9 +3075,6 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 			filemap_invalidate_unlock_shared(mapping);
 			return VM_FAULT_OOM;
 		}
-	} else if (unlikely(!PageUptodate(page))) {
-		filemap_invalidate_lock_shared(mapping);
-		mapping_locked = true;
 	}
 
 	if (!lock_page_maybe_drop_mmap(vmf, page, &fpin))

WARNING: multiple messages have this Message-ID
From: Christoph Hellwig <hch@infradead.org>
To: Jan Kara <jack@suse.cz>
Cc: linux-xfs@vger.kernel.org, Ted Tso <tytso@mit.edu>,
	linux-cifs@vger.kernel.org, "Darrick J. Wong" <djwong@kernel.org>,
	Dave Chinner <david@fromorbit.com>,
	Matthew Wilcox <willy@infradead.org>,
	linux-f2fs-devel@lists.sourceforge.net,
	Christoph Hellwig <hch@infradead.org>,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [f2fs-dev] [PATCH 03/14] mm: Protect operations adding pages to page cache with invalidate_lock
Date: Tue, 13 Jul 2021 07:25:05 +0100	[thread overview]
Message-ID: <YO0xwY+q7d8rQE3f@infradead.org> (raw)
In-Reply-To: <20210712165609.13215-3-jack@suse.cz>

Still looks good.  That being said the additional conditional locking in
filemap_fault makes it fall over the readbility cliff for me.  Something
like this on top of your series would help:

diff --git a/mm/filemap.c b/mm/filemap.c
index fd3f94d36c49..0fad08331cf4 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3040,21 +3040,23 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 	 * Do we have something in the page cache already?
 	 */
 	page = find_get_page(mapping, offset);
-	if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
+	if (likely(page)) {
 		/*
-		 * We found the page, so try async readahead before
-		 * waiting for the lock.
+		 * We found the page, so try async readahead before waiting for
+		 * the lock.
 		 */
-		fpin = do_async_mmap_readahead(vmf, page);
-	} else if (!page) {
+		if (!(vmf->flags & FAULT_FLAG_TRIED))
+			fpin = do_async_mmap_readahead(vmf, page);
+		if (unlikely(!PageUptodate(page))) {
+			filemap_invalidate_lock_shared(mapping);
+			mapping_locked = true;
+		}
+	} else {
 		/* No page in the page cache at all */
 		count_vm_event(PGMAJFAULT);
 		count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
 		ret = VM_FAULT_MAJOR;
 		fpin = do_sync_mmap_readahead(vmf);
-	}
-
-	if (!page) {
 retry_find:
 		/*
 		 * See comment in filemap_create_page() why we need
@@ -3073,9 +3075,6 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 			filemap_invalidate_unlock_shared(mapping);
 			return VM_FAULT_OOM;
 		}
-	} else if (unlikely(!PageUptodate(page))) {
-		filemap_invalidate_lock_shared(mapping);
-		mapping_locked = true;
 	}
 
 	if (!lock_page_maybe_drop_mmap(vmf, page, &fpin))


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  parent reply	other threads:[~2021-07-13  6:25 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-12 16:55 [PATCH 0/14 v9] fs: Hole punch vs page cache filling races Jan Kara
2021-07-12 16:55 ` [f2fs-dev] " Jan Kara
2021-07-12 16:55 ` [PATCH 01/14] mm: Fix comments mentioning i_mutex Jan Kara
2021-07-12 16:55   ` [f2fs-dev] " Jan Kara
2021-07-12 16:55 ` [PATCH 02/14] documentation: Sync file_operations members with reality Jan Kara
2021-07-12 16:55   ` [f2fs-dev] " Jan Kara
2021-07-13  1:02   ` Darrick J. Wong
2021-07-13  1:02     ` [f2fs-dev] " Darrick J. Wong
2021-07-12 16:55 ` [PATCH 03/14] mm: Protect operations adding pages to page cache with invalidate_lock Jan Kara
2021-07-12 16:55   ` [f2fs-dev] " Jan Kara
2021-07-13  1:25   ` Darrick J. Wong
2021-07-13  1:25     ` [f2fs-dev] " Darrick J. Wong
2021-07-13 11:11     ` Jan Kara
2021-07-13 11:11       ` [f2fs-dev] " Jan Kara
2021-07-13  6:25   ` Christoph Hellwig [this message]
2021-07-13  6:25     ` Christoph Hellwig
2021-07-13 12:35     ` Jan Kara
2021-07-13 12:35       ` [f2fs-dev] " Jan Kara
2021-07-12 16:55 ` [PATCH 04/14] mm: Add functions to lock invalidate_lock for two mappings Jan Kara
2021-07-12 16:55   ` [f2fs-dev] " Jan Kara
2021-07-12 16:55 ` [PATCH 05/14] ext4: Convert to use mapping->invalidate_lock Jan Kara
2021-07-12 16:55   ` [f2fs-dev] " Jan Kara
2021-07-12 16:55 ` [PATCH 06/14] ext2: Convert to using invalidate_lock Jan Kara
2021-07-12 16:55   ` [f2fs-dev] " Jan Kara
2021-07-12 16:55 ` [PATCH 07/14] xfs: Refactor xfs_isilocked() Jan Kara
2021-07-12 16:55   ` [f2fs-dev] " Jan Kara
2021-07-12 16:55 ` [PATCH 08/14] xfs: Convert to use invalidate_lock Jan Kara
2021-07-12 16:55   ` [f2fs-dev] " Jan Kara
2021-07-12 16:56 ` [PATCH 09/14] xfs: Convert double locking of MMAPLOCK to use VFS helpers Jan Kara
2021-07-12 16:56   ` [f2fs-dev] " Jan Kara
2021-07-12 16:56 ` [PATCH 10/14] zonefs: Convert to using invalidate_lock Jan Kara
2021-07-12 16:56   ` [f2fs-dev] " Jan Kara
2021-07-12 16:56 ` [PATCH 11/14] f2fs: " Jan Kara
2021-07-12 16:56   ` [f2fs-dev] " Jan Kara
2021-07-12 16:56 ` [PATCH 12/14] fuse: " Jan Kara
2021-07-12 16:56   ` [f2fs-dev] " Jan Kara
2021-07-12 16:56 ` [PATCH 13/14] ceph: Fix race between hole punch and page fault Jan Kara
2021-07-12 16:56   ` [f2fs-dev] " Jan Kara
2021-07-12 16:56 ` [PATCH 14/14] cifs: " Jan Kara
2021-07-12 16:56   ` [f2fs-dev] " Jan Kara
  -- strict thread matches above, loose matches on Subject: below --
2021-07-15 13:40 [PATCH 0/14 v10] fs: Hole punch vs page cache filling races Jan Kara
2021-07-15 13:40 ` [PATCH 03/14] mm: Protect operations adding pages to page cache with invalidate_lock Jan Kara
2021-06-15  9:17 [PATCH 0/14 v8] fs: Hole punch vs page cache filling races Jan Kara
2021-06-15  9:17 ` [PATCH 03/14] mm: Protect operations adding pages to page cache with invalidate_lock Jan Kara
2021-06-16  5:33   ` Christoph Hellwig
2021-06-17 16:15   ` Darrick J. Wong
2021-06-07 14:52 [PATCH 0/14 v7] fs: Hole punch vs page cache filling races Jan Kara
2021-06-07 14:52 ` [PATCH 03/14] mm: Protect operations adding pages to page cache with invalidate_lock Jan Kara
2021-06-07 16:09   ` Darrick J. Wong
2021-06-08 12:19     ` Jan Kara

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