The patch titled
Subject: mm/memcg: warning on !memcg after readahead page charged
has been added to the -mm tree. Its filename is
mm-memcg-warning-on-memcg-after-readahead-page-charged.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-warning-on-memcg-after-readahead-page-charged.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-warning-on-memcg-after-readahead-page-charged.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
Subject: mm/memcg: warning on !memcg after readahead page charged
Since readahead page is charged on memcg too, in theory we don't have to
check this exception now. Before safely remove them all, add a warning
for the unexpected !memcg.
Link: http://lkml.kernel.org/r/1597144232-11370-1-git-send-email-alex.shi@xxxxxxxxxxxxxxxxx
Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Wei Yang <richard.weiyang@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmdebug.h | 13 +++++++++++++
mm/memcontrol.c | 15 ++++++++-------
2 files changed, 21 insertions(+), 7 deletions(-)
--- a/include/linux/mmdebug.h~mm-memcg-warning-on-memcg-after-readahead-page-charged
+++ a/include/linux/mmdebug.h
@@ -37,6 +37,18 @@ void dump_mm(const struct mm_struct *mm)
BUG(); \
} \
} while (0)
+#define VM_WARN_ON_ONCE_PAGE(cond, page) ({ \
+ static bool __section(.data.once) __warned; \
+ int __ret_warn_once = !!(cond); \
+ \
+ if (unlikely(__ret_warn_once && !__warned)) { \
+ dump_page(page, "VM_WARN_ON_ONCE_PAGE(" __stringify(cond)")");\
+ __warned = true; \
+ WARN_ON(1); \
+ } \
+ unlikely(__ret_warn_once); \
+})
+
#define VM_WARN_ON(cond) (void)WARN_ON(cond)
#define VM_WARN_ON_ONCE(cond) (void)WARN_ON_ONCE(cond)
#define VM_WARN_ONCE(cond, format...) (void)WARN_ONCE(cond, format)
@@ -48,6 +60,7 @@ void dump_mm(const struct mm_struct *mm)
#define VM_BUG_ON_MM(cond, mm) VM_BUG_ON(cond)
#define VM_WARN_ON(cond) BUILD_BUG_ON_INVALID(cond)
#define VM_WARN_ON_ONCE(cond) BUILD_BUG_ON_INVALID(cond)
+#define VM_WARN_ON_ONCE_PAGE(cond, page) BUILD_BUG_ON_INVALID(cond)
#define VM_WARN_ONCE(cond, format...) BUILD_BUG_ON_INVALID(cond)
#define VM_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond)
#endif
--- a/mm/memcontrol.c~mm-memcg-warning-on-memcg-after-readahead-page-charged
+++ a/mm/memcontrol.c
@@ -1322,10 +1322,8 @@ struct lruvec *mem_cgroup_page_lruvec(st
}
memcg = page->mem_cgroup;
- /*
- * Swapcache readahead pages are added to the LRU - and
- * possibly migrated - before they are charged.
- */
+ /* Readahead page is charged too, to see if other page uncharged */
+ VM_WARN_ON_ONCE_PAGE(!memcg, page);
if (!memcg)
memcg = root_mem_cgroup;
@@ -6906,8 +6904,9 @@ void mem_cgroup_migrate(struct page *old
if (newpage->mem_cgroup)
return;
- /* Swapcache readahead pages can get replaced before being charged */
memcg = oldpage->mem_cgroup;
+ /* Readahead page is charged too, to see if other page uncharged */
+ VM_WARN_ON_ONCE_PAGE(!memcg, oldpage);
if (!memcg)
return;
@@ -7104,7 +7103,8 @@ void mem_cgroup_swapout(struct page *pag
memcg = page->mem_cgroup;
- /* Readahead page, never charged */
+ /* Readahead page is charged too, to see if other page uncharged */
+ VM_WARN_ON_ONCE_PAGE(!memcg, page);
if (!memcg)
return;
@@ -7168,7 +7168,8 @@ int mem_cgroup_try_charge_swap(struct pa
memcg = page->mem_cgroup;
- /* Readahead page, never charged */
+ /* Readahead page is charged too, to see if other page uncharged */
+ VM_WARN_ON_ONCE_PAGE(!memcg, page);
if (!memcg)
return 0;
_
Patches currently in -mm which might be from alex.shi@xxxxxxxxxxxxxxxxx are
mm-memcg-warning-on-memcg-after-readahead-page-charged.patch
mm-memcg-remove-useless-check-on-page-mem_cgroup.patch
mm-thp-move-lru_add_page_tail-func-to-huge_memoryc.patch
mm-thp-clean-up-lru_add_page_tail.patch
mm-thp-remove-code-path-which-never-got-into.patch
mm-thp-narrow-lru-locking.patch
