Commit a4055888 authored by Alex Shi's avatar Alex Shi Committed by Linus Torvalds
Browse files

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

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: default avatarAlex Shi <alex.shi@linux.alibaba.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 76358ab5

include/linux/mmdebug.h

+13 −0
Original line number Diff line number Diff line
@@ -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

mm/memcontrol.c

+4 −6
Original line number Diff line number Diff line
@@ -1362,10 +1362,7 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd 
	}



	memcg = page_memcg(page);

	/*

	 * Swapcache readahead pages are added to the LRU - and

	 * possibly migrated - before they are charged.

	 */

	VM_WARN_ON_ONCE_PAGE(!memcg, page);

	if (!memcg)

		memcg = root_mem_cgroup;
@@ -6987,6 +6984,7 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage) 
		return;



	memcg = page_memcg(oldpage);

	VM_WARN_ON_ONCE_PAGE(!memcg, oldpage);

	if (!memcg)

		return;
@@ -7186,7 +7184,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) 


	memcg = page_memcg(page);



	/* Readahead page, never charged */

	VM_WARN_ON_ONCE_PAGE(!memcg, page);

	if (!memcg)

		return;
@@ -7253,7 +7251,7 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) 


	memcg = page_memcg(page);



	/* Readahead page, never charged */

	VM_WARN_ON_ONCE_PAGE(!memcg, page);

	if (!memcg)

		return 0;

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