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mm/memcg: warning on !memcg after readahead page charged

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Add VM_WARN_ON_ONCE_PAGE() macro.

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: https://lkml.kernel.org/r/1604283436-18880-3-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alex Shi 2020-12-18 14:01:31 -08:00 committed by Linus Torvalds
parent 76358ab547
commit a405588862
2 changed files with 17 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
include/linux/mmdebug.h
View File

@ -37,6 +37,18 @@ void dump_mm(const struct mm_struct *mm);
BUG(); \ BUG(); \
} \ } \
} while (0) } 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(cond) (void)WARN_ON(cond)
#define VM_WARN_ON_ONCE(cond) (void)WARN_ON_ONCE(cond) #define VM_WARN_ON_ONCE(cond) (void)WARN_ON_ONCE(cond)
#define VM_WARN_ONCE(cond, format...) (void)WARN_ONCE(cond, format) #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_BUG_ON_MM(cond, mm) VM_BUG_ON(cond)
#define VM_WARN_ON(cond) BUILD_BUG_ON_INVALID(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(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_ONCE(cond, format...) BUILD_BUG_ON_INVALID(cond)
#define VM_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond) #define VM_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond)
#endif #endif

10
mm/memcontrol.c
View File

@ -1362,10 +1362,7 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd
} }
memcg = page_memcg(page); memcg = page_memcg(page);
/* VM_WARN_ON_ONCE_PAGE(!memcg, page);
* Swapcache readahead pages are added to the LRU - and
* possibly migrated - before they are charged.
*/
if (!memcg) if (!memcg)
memcg = root_mem_cgroup; memcg = root_mem_cgroup;
@ -6987,6 +6984,7 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
return; return;
memcg = page_memcg(oldpage); memcg = page_memcg(oldpage);
VM_WARN_ON_ONCE_PAGE(!memcg, oldpage);
if (!memcg) if (!memcg)
return; return;
@ -7186,7 +7184,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
memcg = page_memcg(page); memcg = page_memcg(page);
/* Readahead page, never charged */ VM_WARN_ON_ONCE_PAGE(!memcg, page);
if (!memcg) if (!memcg)
return; return;
@ -7253,7 +7251,7 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
memcg = page_memcg(page); memcg = page_memcg(page);
/* Readahead page, never charged */ VM_WARN_ON_ONCE_PAGE(!memcg, page);
if (!memcg) if (!memcg)
return 0; return 0;