From: Jan Kara <jack@suse.cz> To: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrew Morton <akpm@linux-foundation.org>, 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: Re: [PATCH 3/9] mm: workingset: turn shadow node shrinker bugs into warnings Date: Fri, 18 Nov 2016 08:32:34 +0100 [thread overview] Message-ID: <20161118073234.GC18676@quack2.suse.cz> (raw) In-Reply-To: <20161117191138.22769-4-hannes@cmpxchg.org> On Thu 17-11-16 14:11:32, Johannes Weiner wrote: > When the shadow page shrinker tries to reclaim a radix tree node but > finds it in an unexpected state - it should contain no pages, and > non-zero shadow entries - there is no need to kill the executing task > or even the entire system. Warn about the invalid state, then leave > that tree node be. Simply don't put it back on the shadow LRU for > future reclaim and move on. > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Looks good. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > mm/workingset.c | 20 ++++++++++++-------- > 1 file changed, 12 insertions(+), 8 deletions(-) > > diff --git a/mm/workingset.c b/mm/workingset.c > index 617475f529f4..3cfc61d84a52 100644 > --- a/mm/workingset.c > +++ b/mm/workingset.c > @@ -418,23 +418,27 @@ static enum lru_status shadow_lru_isolate(struct list_head *item, > * no pages, so we expect to be able to remove them all and > * delete and free the empty node afterwards. > */ > - BUG_ON(!workingset_node_shadows(node)); > - BUG_ON(workingset_node_pages(node)); > - > + if (WARN_ON_ONCE(!workingset_node_shadows(node))) > + goto out_invalid; > + if (WARN_ON_ONCE(workingset_node_pages(node))) > + goto out_invalid; > for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { > if (node->slots[i]) { > - BUG_ON(!radix_tree_exceptional_entry(node->slots[i])); > + if (WARN_ON_ONCE(!radix_tree_exceptional_entry(node->slots[i]))) > + goto out_invalid; > + if (WARN_ON_ONCE(!mapping->nrexceptional)) > + goto out_invalid; > node->slots[i] = NULL; > workingset_node_shadows_dec(node); > - BUG_ON(!mapping->nrexceptional); > mapping->nrexceptional--; > } > } > - BUG_ON(workingset_node_shadows(node)); > + if (WARN_ON_ONCE(workingset_node_shadows(node))) > + goto out_invalid; > inc_node_state(page_pgdat(virt_to_page(node)), WORKINGSET_NODERECLAIM); > - if (!__radix_tree_delete_node(&mapping->page_tree, node)) > - BUG(); > + __radix_tree_delete_node(&mapping->page_tree, node); > > +out_invalid: > spin_unlock(&mapping->tree_lock); > ret = LRU_REMOVED_RETRY; > out: > -- > 2.10.2 > -- Jan Kara <jack@suse.com> SUSE Labs, CR
WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack@suse.cz> To: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrew Morton <akpm@linux-foundation.org>, 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: Re: [PATCH 3/9] mm: workingset: turn shadow node shrinker bugs into warnings Date: Fri, 18 Nov 2016 08:32:34 +0100 [thread overview] Message-ID: <20161118073234.GC18676@quack2.suse.cz> (raw) In-Reply-To: <20161117191138.22769-4-hannes@cmpxchg.org> On Thu 17-11-16 14:11:32, Johannes Weiner wrote: > When the shadow page shrinker tries to reclaim a radix tree node but > finds it in an unexpected state - it should contain no pages, and > non-zero shadow entries - there is no need to kill the executing task > or even the entire system. Warn about the invalid state, then leave > that tree node be. Simply don't put it back on the shadow LRU for > future reclaim and move on. > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Looks good. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > mm/workingset.c | 20 ++++++++++++-------- > 1 file changed, 12 insertions(+), 8 deletions(-) > > diff --git a/mm/workingset.c b/mm/workingset.c > index 617475f529f4..3cfc61d84a52 100644 > --- a/mm/workingset.c > +++ b/mm/workingset.c > @@ -418,23 +418,27 @@ static enum lru_status shadow_lru_isolate(struct list_head *item, > * no pages, so we expect to be able to remove them all and > * delete and free the empty node afterwards. > */ > - BUG_ON(!workingset_node_shadows(node)); > - BUG_ON(workingset_node_pages(node)); > - > + if (WARN_ON_ONCE(!workingset_node_shadows(node))) > + goto out_invalid; > + if (WARN_ON_ONCE(workingset_node_pages(node))) > + goto out_invalid; > for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { > if (node->slots[i]) { > - BUG_ON(!radix_tree_exceptional_entry(node->slots[i])); > + if (WARN_ON_ONCE(!radix_tree_exceptional_entry(node->slots[i]))) > + goto out_invalid; > + if (WARN_ON_ONCE(!mapping->nrexceptional)) > + goto out_invalid; > node->slots[i] = NULL; > workingset_node_shadows_dec(node); > - BUG_ON(!mapping->nrexceptional); > mapping->nrexceptional--; > } > } > - BUG_ON(workingset_node_shadows(node)); > + if (WARN_ON_ONCE(workingset_node_shadows(node))) > + goto out_invalid; > inc_node_state(page_pgdat(virt_to_page(node)), WORKINGSET_NODERECLAIM); > - if (!__radix_tree_delete_node(&mapping->page_tree, node)) > - BUG(); > + __radix_tree_delete_node(&mapping->page_tree, node); > > +out_invalid: > spin_unlock(&mapping->tree_lock); > ret = LRU_REMOVED_RETRY; > out: > -- > 2.10.2 > -- Jan Kara <jack@suse.com> SUSE Labs, CR -- 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:[~2016-11-18 7:32 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 [this message] 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 ` [PATCH 9/9] mm: workingset: restore refault tracking for single-page files Johannes Weiner 2016-11-17 19:32 ` Johannes Weiner 2016-11-18 8:30 ` Jan Kara 2016-11-18 8:30 ` Jan Kara
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