From: Johannes Weiner <hannes@cmpxchg.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: Jan Kara <jack@suse.cz>, "Kirill A. Shutemov" <kirill@shutemov.name>, Linus Torvalds <torvalds@linux-foundation.org>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH 9/9] mm: workingset: restore refault tracking for single-page files Date: Thu, 17 Nov 2016 14:32:44 -0500 [thread overview] Message-ID: <20161117193244.GF23430@cmpxchg.org> (raw) In-Reply-To: <20161117191138.22769-1-hannes@cmpxchg.org> Shadow entries in the page cache used to be accounted behind the radix tree implementation's back in the upper bits of node->count, and the radix tree code extending a single-entry tree with a shadow entry in root->rnode would corrupt that counter. As a result, we could not put shadow entries at index 0 if the tree didn't have any other entries, and that means no refault detection for any single-page file. Now that the shadow entries are tracked natively in the radix tree's exceptional counter, this is no longer necessary. Extending and shrinking the tree from and to single entries in root->rnode now does the right thing when the entry is exceptional, remove that limitation. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> --- mm/filemap.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 7d92032277ff..ae7b6992aded 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -164,14 +164,7 @@ static void page_cache_tree_delete(struct address_space *mapping, __radix_tree_lookup(&mapping->page_tree, page->index + i, &node, &slot); - if (!node) { - VM_BUG_ON_PAGE(nr != 1, page); - /* - * We need a node to properly account shadow - * entries. Don't plant any without. XXX - */ - shadow = NULL; - } + VM_BUG_ON_PAGE(!node && nr != 1, page); radix_tree_clear_tags(&mapping->page_tree, node, slot); __radix_tree_replace(&mapping->page_tree, node, slot, shadow, -- 2.10.2
WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: Jan Kara <jack@suse.cz>, "Kirill A. Shutemov" <kirill@shutemov.name>, Linus Torvalds <torvalds@linux-foundation.org>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH 9/9] mm: workingset: restore refault tracking for single-page files Date: Thu, 17 Nov 2016 14:32:44 -0500 [thread overview] Message-ID: <20161117193244.GF23430@cmpxchg.org> (raw) In-Reply-To: <20161117191138.22769-1-hannes@cmpxchg.org> Shadow entries in the page cache used to be accounted behind the radix tree implementation's back in the upper bits of node->count, and the radix tree code extending a single-entry tree with a shadow entry in root->rnode would corrupt that counter. As a result, we could not put shadow entries at index 0 if the tree didn't have any other entries, and that means no refault detection for any single-page file. Now that the shadow entries are tracked natively in the radix tree's exceptional counter, this is no longer necessary. Extending and shrinking the tree from and to single entries in root->rnode now does the right thing when the entry is exceptional, remove that limitation. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> --- mm/filemap.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 7d92032277ff..ae7b6992aded 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -164,14 +164,7 @@ static void page_cache_tree_delete(struct address_space *mapping, __radix_tree_lookup(&mapping->page_tree, page->index + i, &node, &slot); - if (!node) { - VM_BUG_ON_PAGE(nr != 1, page); - /* - * We need a node to properly account shadow - * entries. Don't plant any without. XXX - */ - shadow = NULL; - } + VM_BUG_ON_PAGE(!node && nr != 1, page); radix_tree_clear_tags(&mapping->page_tree, node, slot); __radix_tree_replace(&mapping->page_tree, node, slot, shadow, -- 2.10.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-11-17 19:32 UTC|newest] Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-11-17 19:11 [PATCH 0/9] mm: workingset: radix tree subtleties & single-page file refaults v3 Johannes Weiner 2016-11-17 19:11 ` Johannes Weiner 2016-11-17 19:11 ` [PATCH 1/9] mm: khugepaged: close use-after-free race during shmem collapsing Johannes Weiner 2016-11-17 19:11 ` Johannes Weiner 2016-11-17 23:19 ` Kirill A. Shutemov 2016-11-17 23:19 ` Kirill A. Shutemov 2016-11-18 7:29 ` Jan Kara 2016-11-18 7:29 ` Jan Kara 2016-11-17 19:11 ` [PATCH 2/9] mm: khugepaged: fix radix tree node leak in shmem collapse error path Johannes Weiner 2016-11-17 19:11 ` Johannes Weiner 2016-11-17 23:21 ` Kirill A. Shutemov 2016-11-17 23:21 ` Kirill A. Shutemov 2016-11-18 7:30 ` Jan Kara 2016-11-18 7:30 ` Jan Kara 2016-11-17 19:11 ` [PATCH 3/9] mm: workingset: turn shadow node shrinker bugs into warnings Johannes Weiner 2016-11-17 19:11 ` Johannes Weiner 2016-11-18 7:32 ` Jan Kara 2016-11-18 7:32 ` Jan Kara 2016-11-17 19:29 ` [PATCH 4/9] lib: radix-tree: native accounting of exceptional entries Johannes Weiner 2016-11-17 19:29 ` Johannes Weiner 2016-11-18 7:39 ` Jan Kara 2016-11-18 7:39 ` Jan Kara 2016-11-17 19:30 ` [PATCH 5/9] lib: radix-tree: check accounting of existing slot replacement users Johannes Weiner 2016-11-17 19:30 ` Johannes Weiner 2016-11-18 7:46 ` Jan Kara 2016-11-18 7:46 ` Jan Kara 2016-11-17 19:30 ` [PATCH 6/9] lib: radix-tree: add entry deletion support to __radix_tree_replace() Johannes Weiner 2016-11-17 19:30 ` Johannes Weiner 2016-11-18 8:13 ` Jan Kara 2016-11-18 8:13 ` Jan Kara 2016-11-17 19:31 ` [PATCH 7/9] lib: radix-tree: update callback for changing leaf nodes Johannes Weiner 2016-11-17 19:31 ` Johannes Weiner 2016-11-18 8:26 ` Jan Kara 2016-11-18 8:26 ` Jan Kara 2016-11-17 19:32 ` [PATCH 8/9] mm: workingset: move shadow entry tracking to radix tree exceptional tracking Johannes Weiner 2016-11-17 19:32 ` Johannes Weiner 2016-11-18 8:29 ` Jan Kara 2016-11-18 8:29 ` Jan Kara 2016-11-17 19:32 ` Johannes Weiner [this message] 2016-11-17 19:32 ` [PATCH 9/9] mm: workingset: restore refault tracking for single-page files Johannes Weiner 2016-11-18 8:30 ` Jan Kara 2016-11-18 8:30 ` Jan Kara
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