From: Hugh Dickins <hughd@google.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Ning Qu <quning@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 01/24] mm: update_lru_size warn and reset bad lru_size
Date: Fri, 20 Feb 2015 19:51:16 -0800 (PST) [thread overview]
Message-ID: <alpine.LSU.2.11.1502201949350.14414@eggly.anvils> (raw)
In-Reply-To: <alpine.LSU.2.11.1502201941340.14414@eggly.anvils>
Though debug kernels have a VM_BUG_ON to help protect from misaccounting
lru_size, non-debug kernels are liable to wrap it around: and then the
vast unsigned long size draws page reclaim into a loop of repeatedly
doing nothing on an empty list, without even a cond_resched().
That soft lockup looks confusingly like an over-busy reclaim scenario,
with lots of contention on the lruvec lock in shrink_inactive_list():
yet has a totally different origin.
Help differentiate with a custom warning in mem_cgroup_update_lru_size(),
even in non-debug kernels; and reset the size to avoid the lockup. But
the particular bug which suggested this change was mine alone, and since
fixed.
Signed-off-by: Hugh Dickins <hughd@google.com>
---
include/linux/mm_inline.h | 2 +-
mm/memcontrol.c | 24 ++++++++++++++++++++----
2 files changed, 21 insertions(+), 5 deletions(-)
--- thpfs.orig/include/linux/mm_inline.h 2013-11-03 15:41:51.000000000 -0800
+++ thpfs/include/linux/mm_inline.h 2015-02-20 19:33:25.928096883 -0800
@@ -35,8 +35,8 @@ static __always_inline void del_page_fro
struct lruvec *lruvec, enum lru_list lru)
{
int nr_pages = hpage_nr_pages(page);
- mem_cgroup_update_lru_size(lruvec, lru, -nr_pages);
list_del(&page->lru);
+ mem_cgroup_update_lru_size(lruvec, lru, -nr_pages);
__mod_zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru, -nr_pages);
}
--- thpfs.orig/mm/memcontrol.c 2015-02-08 18:54:22.000000000 -0800
+++ thpfs/mm/memcontrol.c 2015-02-20 19:33:25.928096883 -0800
@@ -1296,22 +1296,38 @@ out:
* @lru: index of lru list the page is sitting on
* @nr_pages: positive when adding or negative when removing
*
- * This function must be called when a page is added to or removed from an
- * lru list.
+ * This function must be called under lruvec lock, just before a page is added
+ * to or just after a page is removed from an lru list (that ordering being so
+ * as to allow it to check that lru_size 0 is consistent with list_empty).
*/
void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
int nr_pages)
{
struct mem_cgroup_per_zone *mz;
unsigned long *lru_size;
+ long size;
+ bool empty;
if (mem_cgroup_disabled())
return;
mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
lru_size = mz->lru_size + lru;
- *lru_size += nr_pages;
- VM_BUG_ON((long)(*lru_size) < 0);
+ empty = list_empty(lruvec->lists + lru);
+
+ if (nr_pages < 0)
+ *lru_size += nr_pages;
+
+ size = *lru_size;
+ if (WARN(size < 0 || empty != !size,
+ "mem_cgroup_update_lru_size(%p, %d, %d): lru_size %ld but %sempty\n",
+ lruvec, lru, nr_pages, size, empty ? "" : "not ")) {
+ VM_BUG_ON(1);
+ *lru_size = 0;
+ }
+
+ if (nr_pages > 0)
+ *lru_size += nr_pages;
}
bool mem_cgroup_is_descendant(struct mem_cgroup *memcg, struct mem_cgroup *root)
--
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next prev parent reply other threads:[~2015-02-21 3:51 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-21 3:49 [PATCH 00/24] huge tmpfs: an alternative approach to THPageCache Hugh Dickins
2015-02-21 3:51 ` Hugh Dickins [this message]
2015-02-23 9:30 ` [PATCH 01/24] mm: update_lru_size warn and reset bad lru_size Kirill A. Shutemov
2015-03-23 2:44 ` Hugh Dickins
2015-02-21 3:54 ` [PATCH 02/24] mm: update_lru_size do the __mod_zone_page_state Hugh Dickins
2015-02-21 3:56 ` [PATCH 03/24] mm: use __SetPageSwapBacked and don't ClearPageSwapBacked Hugh Dickins
2015-02-25 10:53 ` Mel Gorman
2015-03-23 3:01 ` Hugh Dickins
2015-02-21 3:58 ` [PATCH 04/24] mm: make page migration's newpage handling more robust Hugh Dickins
2015-02-21 4:00 ` [PATCH 05/24] tmpfs: preliminary minor tidyups Hugh Dickins
2015-02-21 4:01 ` [PATCH 06/24] huge tmpfs: prepare counts in meminfo, vmstat and SysRq-m Hugh Dickins
2015-02-21 4:03 ` [PATCH 07/24] huge tmpfs: include shmem freeholes in available memory counts Hugh Dickins
2015-02-21 4:05 ` [PATCH 08/24] huge tmpfs: prepare huge=N mount option and /proc/sys/vm/shmem_huge Hugh Dickins
2015-02-21 4:06 ` [PATCH 09/24] huge tmpfs: try to allocate huge pages, split into a team Hugh Dickins
2015-02-21 4:07 ` [PATCH 10/24] huge tmpfs: avoid team pages in a few places Hugh Dickins
2015-02-21 4:09 ` [PATCH 11/24] huge tmpfs: shrinker to migrate and free underused holes Hugh Dickins
2015-03-19 16:56 ` Konstantin Khlebnikov
2015-03-23 4:40 ` Hugh Dickins
2015-03-23 12:50 ` Kirill A. Shutemov
2015-03-23 13:50 ` Kirill A. Shutemov
2015-03-24 12:57 ` Kirill A. Shutemov
2015-03-25 0:41 ` Hugh Dickins
2015-02-21 4:11 ` [PATCH 12/24] huge tmpfs: get_unmapped_area align and fault supply huge page Hugh Dickins
2015-02-21 4:12 ` [PATCH 13/24] huge tmpfs: extend get_user_pages_fast to shmem pmd Hugh Dickins
2015-02-21 4:13 ` [PATCH 14/24] huge tmpfs: extend vma_adjust_trans_huge " Hugh Dickins
2015-02-21 4:15 ` [PATCH 15/24] huge tmpfs: rework page_referenced_one and try_to_unmap_one Hugh Dickins
2015-02-21 4:16 ` [PATCH 16/24] huge tmpfs: fix problems from premature exposure of pagetable Hugh Dickins
2015-07-01 10:53 ` Kirill A. Shutemov
2015-02-21 4:18 ` [PATCH 17/24] huge tmpfs: map shmem by huge page pmd or by page team ptes Hugh Dickins
2015-02-21 4:20 ` [PATCH 18/24] huge tmpfs: mmap_sem is unlocked when truncation splits huge pmd Hugh Dickins
2015-02-21 4:22 ` [PATCH 19/24] huge tmpfs: disband split huge pmds on race or memory failure Hugh Dickins
2015-02-21 4:23 ` [PATCH 20/24] huge tmpfs: use Unevictable lru with variable hpage_nr_pages() Hugh Dickins
2015-02-21 4:25 ` [PATCH 21/24] huge tmpfs: fix Mlocked meminfo, tracking huge and unhuge mlocks Hugh Dickins
2015-02-21 4:27 ` [PATCH 22/24] huge tmpfs: fix Mapped meminfo, tracking huge and unhuge mappings Hugh Dickins
2015-02-21 4:29 ` [PATCH 23/24] kvm: plumb return of hva when resolving page fault Hugh Dickins
2015-02-21 4:31 ` [PATCH 24/24] kvm: teach kvm to map page teams as huge pages Hugh Dickins
2015-02-23 13:48 ` [PATCH 00/24] huge tmpfs: an alternative approach to THPageCache Kirill A. Shutemov
2015-03-23 2:25 ` Hugh Dickins
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