From ae026b2aa19350f3c863df2dce7e0511dd78ff49 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Fri, 17 Jul 2015 16:23:48 -0700 Subject: mm, meminit: suppress unused memory variable warning The kbuild test robot reported the following tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 14a6f1989dae9445d4532941bdd6bbad84f4c8da commit: 3b242c66ccbd60cf47ab0e8992119d9617548c23 x86: mm: enable deferred struct page initialisation on x86-64 date: 3 days ago config: x86_64-randconfig-x006-201527 (attached as .config) reproduce: git checkout 3b242c66ccbd60cf47ab0e8992119d9617548c23 # save the attached .config to linux build tree make ARCH=x86_64 All warnings (new ones prefixed by >>): mm/page_alloc.c: In function 'early_page_uninitialised': >> mm/page_alloc.c:247:6: warning: unused variable 'nid' [-Wunused-variable] int nid = early_pfn_to_nid(pfn); It's due to the NODE_DATA macro ignoring the nid parameter on !NUMA configurations. This patch avoids the warning by not declaring nid. Signed-off-by: Mel Gorman Reported-by: Wu Fengguang Cc: "Kirill A. Shutemov" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'mm/page_alloc.c') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 506eac8b38af..ac05e7ae399e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -246,9 +246,7 @@ static inline void reset_deferred_meminit(pg_data_t *pgdat) /* Returns true if the struct page for the pfn is uninitialised */ static inline bool __meminit early_page_uninitialised(unsigned long pfn) { - int nid = early_pfn_to_nid(pfn); - - if (pfn >= NODE_DATA(nid)->first_deferred_pfn) + if (pfn >= NODE_DATA(early_pfn_to_nid(pfn))->first_deferred_pfn) return true; return false; -- cgit v1.2.3-70-g09d2 From f3a14ced32513d103a3ed0ce89c4e713fac01461 Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Fri, 17 Jul 2015 16:24:15 -0700 Subject: mm/page_owner: fix possible access violation When I tested my new patches, I found that page pointer which is used for setting page_owner information is changed. This is because page pointer is used to set new migratetype in loop. After this work, page pointer could be out of bound. If this wrong pointer is used for page_owner, access violation happens. Below is error message that I got. BUG: unable to handle kernel paging request at 0000000000b00018 IP: [] save_stack_address+0x30/0x40 PGD 1af2d067 PUD 166e0067 PMD 0 Oops: 0002 [#1] SMP ...snip... Call Trace: print_context_stack+0xcf/0x100 dump_trace+0x15f/0x320 save_stack_trace+0x2f/0x50 __set_page_owner+0x46/0x70 __isolate_free_page+0x1f7/0x210 split_free_page+0x21/0xb0 isolate_freepages_block+0x1e2/0x410 compaction_alloc+0x22d/0x2d0 migrate_pages+0x289/0x8b0 compact_zone+0x409/0x880 compact_zone_order+0x6d/0x90 try_to_compact_pages+0x110/0x210 __alloc_pages_direct_compact+0x3d/0xe6 __alloc_pages_nodemask+0x6cd/0x9a0 alloc_pages_current+0x91/0x100 runtest_store+0x296/0xa50 simple_attr_write+0xbd/0xe0 __vfs_write+0x28/0xf0 vfs_write+0xa9/0x1b0 SyS_write+0x46/0xb0 system_call_fastpath+0x16/0x75 This patch fixes this error by moving up set_page_owner(). Signed-off-by: Joonsoo Kim Cc: Mel Gorman Cc: Vlastimil Babka Acked-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'mm/page_alloc.c') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ac05e7ae399e..fbba675a0bd9 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1994,6 +1994,8 @@ int __isolate_free_page(struct page *page, unsigned int order) zone->free_area[order].nr_free--; rmv_page_order(page); + set_page_owner(page, order, 0); + /* Set the pageblock if the isolated page is at least a pageblock */ if (order >= pageblock_order - 1) { struct page *endpage = page + (1 << order) - 1; @@ -2005,7 +2007,7 @@ int __isolate_free_page(struct page *page, unsigned int order) } } - set_page_owner(page, order, 0); + return 1UL << order; } -- cgit v1.2.3-70-g09d2 From e2cfc91120fa01e3458167054af993fb83d7d0ec Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Fri, 17 Jul 2015 16:24:18 -0700 Subject: mm/page_owner: set correct gfp_mask on page_owner Currently, we set wrong gfp_mask to page_owner info in case of isolated freepage by compaction and split page. It causes incorrect mixed pageblock report that we can get from '/proc/pagetypeinfo'. This metric is really useful to measure fragmentation effect so should be accurate. This patch fixes it by setting correct information. Without this patch, after kernel build workload is finished, number of mixed pageblock is 112 among roughly 210 movable pageblocks. But, with this fix, output shows that mixed pageblock is just 57. Signed-off-by: Joonsoo Kim Cc: Mel Gorman Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/page_owner.h | 13 +++++++++++++ mm/page_alloc.c | 8 +++++--- mm/page_owner.c | 7 +++++++ 3 files changed, 25 insertions(+), 3 deletions(-) (limited to 'mm/page_alloc.c') diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h index b48c3471c254..cacaabea8a09 100644 --- a/include/linux/page_owner.h +++ b/include/linux/page_owner.h @@ -8,6 +8,7 @@ extern struct page_ext_operations page_owner_ops; extern void __reset_page_owner(struct page *page, unsigned int order); extern void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask); +extern gfp_t __get_page_owner_gfp(struct page *page); static inline void reset_page_owner(struct page *page, unsigned int order) { @@ -25,6 +26,14 @@ static inline void set_page_owner(struct page *page, __set_page_owner(page, order, gfp_mask); } + +static inline gfp_t get_page_owner_gfp(struct page *page) +{ + if (likely(!page_owner_inited)) + return 0; + + return __get_page_owner_gfp(page); +} #else static inline void reset_page_owner(struct page *page, unsigned int order) { @@ -33,6 +42,10 @@ static inline void set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask) { } +static inline gfp_t get_page_owner_gfp(struct page *page) +{ + return 0; +} #endif /* CONFIG_PAGE_OWNER */ #endif /* __LINUX_PAGE_OWNER_H */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index fbba675a0bd9..ef19f22b2b7d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1948,6 +1948,7 @@ void free_hot_cold_page_list(struct list_head *list, bool cold) void split_page(struct page *page, unsigned int order) { int i; + gfp_t gfp_mask; VM_BUG_ON_PAGE(PageCompound(page), page); VM_BUG_ON_PAGE(!page_count(page), page); @@ -1961,10 +1962,11 @@ void split_page(struct page *page, unsigned int order) split_page(virt_to_page(page[0].shadow), order); #endif - set_page_owner(page, 0, 0); + gfp_mask = get_page_owner_gfp(page); + set_page_owner(page, 0, gfp_mask); for (i = 1; i < (1 << order); i++) { set_page_refcounted(page + i); - set_page_owner(page + i, 0, 0); + set_page_owner(page + i, 0, gfp_mask); } } EXPORT_SYMBOL_GPL(split_page); @@ -1994,7 +1996,7 @@ int __isolate_free_page(struct page *page, unsigned int order) zone->free_area[order].nr_free--; rmv_page_order(page); - set_page_owner(page, order, 0); + set_page_owner(page, order, __GFP_MOVABLE); /* Set the pageblock if the isolated page is at least a pageblock */ if (order >= pageblock_order - 1) { diff --git a/mm/page_owner.c b/mm/page_owner.c index bd5f842b56d2..983c3a10fa07 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -76,6 +76,13 @@ void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask) __set_bit(PAGE_EXT_OWNER, &page_ext->flags); } +gfp_t __get_page_owner_gfp(struct page *page) +{ + struct page_ext *page_ext = lookup_page_ext(page); + + return page_ext->gfp_mask; +} + static ssize_t print_page_owner(char __user *buf, size_t count, unsigned long pfn, struct page *page, struct page_ext *page_ext) -- cgit v1.2.3-70-g09d2