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Commit acda305d authored by Yang Shi's avatar Yang Shi Committed by Prakash Gupta
Browse files

mm: check the return value of lookup_page_ext for all call sites 

Per the discussion with Joonsoo Kim [1], we need check the return value
of lookup_page_ext() for all call sites since it might return NULL in
some cases, although it is unlikely, i.e.  memory hotplug.

Tested with ltp with "page_owner=0".

[1] http://lkml.kernel.org/r/20160519002809.GA10245@js1304-P5Q-DELUXE

Change-Id: Ie0c577c1136a7f6f4e0fa2ceacfb007cd5323b8e
[akpm@linux-foundation.org: fix build-breaking typos]
[arnd@arndb.de: fix build problems from lookup_page_ext]
  Link: http://lkml.kernel.org/r/6285269.2CksypHdYp@wuerfel
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1464023768-31025-1-git-send-email-yang.shi@linaro.org


Signed-off-by: default avatarYang Shi <yang.shi@linaro.org>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Git-commit: f86e4271978bd93db466d6a95dad4b0fdcdb04f6
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


[guptap@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: default avatarPrakash Gupta <guptap@codeaurora.org>
parent dcaff0c9

include/linux/page_idle.h

+36 −7
Original line number Diff line number Diff line
@@ -46,33 +46,62 @@ extern struct page_ext_operations page_idle_ops; 


static inline bool page_is_young(struct page *page)

{

	return test_bit(PAGE_EXT_YOUNG, &lookup_page_ext(page)->flags);

	struct page_ext *page_ext = lookup_page_ext(page);



	if (unlikely(!page_ext))

		return false;



	return test_bit(PAGE_EXT_YOUNG, &page_ext->flags);

}



static inline void set_page_young(struct page *page)

{

	set_bit(PAGE_EXT_YOUNG, &lookup_page_ext(page)->flags);

	struct page_ext *page_ext = lookup_page_ext(page);



	if (unlikely(!page_ext))

		return;



	set_bit(PAGE_EXT_YOUNG, &page_ext->flags);

}



static inline bool test_and_clear_page_young(struct page *page)

{

	return test_and_clear_bit(PAGE_EXT_YOUNG,

				  &lookup_page_ext(page)->flags);

	struct page_ext *page_ext = lookup_page_ext(page);



	if (unlikely(!page_ext))

		return false;



	return test_and_clear_bit(PAGE_EXT_YOUNG, &page_ext->flags);

}



static inline bool page_is_idle(struct page *page)

{

	return test_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);

	struct page_ext *page_ext = lookup_page_ext(page);



	if (unlikely(!page_ext))

		return false;



	return test_bit(PAGE_EXT_IDLE, &page_ext->flags);

}



static inline void set_page_idle(struct page *page)

{

	set_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);

	struct page_ext *page_ext = lookup_page_ext(page);



	if (unlikely(!page_ext))

		return;



	set_bit(PAGE_EXT_IDLE, &page_ext->flags);

}



static inline void clear_page_idle(struct page *page)

{

	clear_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);

	struct page_ext *page_ext = lookup_page_ext(page);



	if (unlikely(!page_ext))

		return;



	clear_bit(PAGE_EXT_IDLE, &page_ext->flags);

}

#endif /* CONFIG_64BIT */

mm/page_alloc.c

+6 −0
Original line number Diff line number Diff line
@@ -584,6 +584,9 @@ static inline void set_page_guard(struct zone *zone, struct page *page, 
		return;



	page_ext = lookup_page_ext(page);

	if (unlikely(!page_ext))

		return;



	__set_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);



	INIT_LIST_HEAD(&page->lru);
@@ -601,6 +604,9 @@ static inline void clear_page_guard(struct zone *zone, struct page *page, 
		return;



	page_ext = lookup_page_ext(page);

	if (unlikely(!page_ext))

		return;



	__clear_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);



	set_page_private(page, 0);

mm/page_owner.c

+26 −0
Original line number Diff line number Diff line
@@ -59,6 +59,8 @@ void __reset_page_owner(struct page *page, unsigned int order) 


	for (i = 0; i < (1 << order); i++) {

		page_ext = lookup_page_ext(page + i);

		if (unlikely(!page_ext))

			continue;

		__clear_bit(PAGE_EXT_OWNER, &page_ext->flags);

	}

}
@@ -66,6 +68,7 @@ void __reset_page_owner(struct page *page, unsigned int order) 
void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)

{

	struct page_ext *page_ext = lookup_page_ext(page);



	struct stack_trace trace = {

		.nr_entries = 0,

		.max_entries = ARRAY_SIZE(page_ext->trace_entries),
@@ -73,6 +76,9 @@ void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask) 
		.skip = 3,

	};



	if (unlikely(!page_ext))

		return;



	save_stack_trace(&trace);



	page_ext->order = order;
@@ -86,6 +92,8 @@ void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask) 
void __set_page_owner_migrate_reason(struct page *page, int reason)

{

	struct page_ext *page_ext = lookup_page_ext(page);

	if (unlikely(!page_ext))

		return;



	page_ext->last_migrate_reason = reason;

}
@@ -94,6 +102,12 @@ void __split_page_owner(struct page *page, unsigned int order) 
{

	int i;

	struct page_ext *page_ext = lookup_page_ext(page);

	if (unlikely(!page_ext))

		/*

		 * The caller just returns if no valid gfp

		 * So return here too.

		 */

		return;



	page_ext->order = 0;

	for (i = 1; i < (1 << order); i++)
@@ -106,6 +120,9 @@ void __copy_page_owner(struct page *oldpage, struct page *newpage) 
	struct page_ext *new_ext = lookup_page_ext(newpage);

	int i;



	if (unlikely(!old_ext || !new_ext))

		return;



	new_ext->order = old_ext->order;

	new_ext->gfp_mask = old_ext->gfp_mask;

	new_ext->last_migrate_reason = old_ext->last_migrate_reason;
@@ -201,6 +218,11 @@ void __dump_page_owner(struct page *page) 
	gfp_t gfp_mask = page_ext->gfp_mask;

	int mt = gfpflags_to_migratetype(gfp_mask);



	if (unlikely(!page_ext)) {

		pr_alert("There is not page extension available.\n");

		return;

	}



	if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {

		pr_alert("page_owner info is not active (free page?)\n");

		return;
@@ -260,6 +282,8 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) 
		}



		page_ext = lookup_page_ext(page);

		if (unlikely(!page_ext))

			continue;



		/*

		 * Some pages could be missed by concurrent allocation or free,
@@ -326,6 +350,8 @@ static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone) 
				continue;



			page_ext = lookup_page_ext(page);

			if (unlikely(!page_ext))

				continue;



			/* Maybe overraping zone */

			if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))

mm/vmstat.c

+2 −0
Original line number Diff line number Diff line
@@ -1090,6 +1090,8 @@ static void pagetypeinfo_showmixedcount_print(struct seq_file *m, 
				continue;



			page_ext = lookup_page_ext(page);

			if (unlikely(!page_ext))

				continue;



			if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))

				continue;