From 4e462112e98f9ad6dd62e160f8b14c7df5fed2fc Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Tue, 15 Mar 2016 14:56:21 -0700 Subject: [PATCH] mm, page_owner: dump page owner info from dump_page() The page_owner mechanism is useful for dealing with memory leaks. By reading /sys/kernel/debug/page_owner one can determine the stack traces leading to allocations of all pages, and find e.g. a buggy driver. This information might be also potentially useful for debugging, such as the VM_BUG_ON_PAGE() calls to dump_page(). So let's print the stored info from dump_page(). Example output: page:ffffea000292f1c0 count:1 mapcount:0 mapping:ffff8800b2f6cc18 index:0x91d flags: 0x1fffff8001002c(referenced|uptodate|lru|mappedtodisk) page dumped because: VM_BUG_ON_PAGE(1) page->mem_cgroup:ffff8801392c5000 page allocated via order 0, migratetype Movable, gfp_mask 0x24213ca(GFP_HIGHUSER_MOVABLE|__GFP_COLD|__GFP_NOWARN|__GFP_NORETRY) [] __alloc_pages_nodemask+0x134/0x230 [] alloc_pages_current+0x88/0x120 [] __page_cache_alloc+0xe6/0x120 [] __do_page_cache_readahead+0xdc/0x240 [] ondemand_readahead+0x135/0x260 [] page_cache_async_readahead+0x6c/0x70 [] generic_file_read_iter+0x3f2/0x760 [] __vfs_read+0xa7/0xd0 page has been migrated, last migrate reason: compaction Signed-off-by: Vlastimil Babka Acked-by: Michal Hocko Cc: Joonsoo Kim Cc: Minchan Kim Cc: Sasha Levin Cc: "Kirill A. Shutemov" Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/page_owner.h | 9 +++++++++ mm/debug.c | 2 ++ mm/page_alloc.c | 1 + mm/page_owner.c | 25 +++++++++++++++++++++++++ 4 files changed, 37 insertions(+) diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h index 555893bf13d7..46f1b939948c 100644 --- a/include/linux/page_owner.h +++ b/include/linux/page_owner.h @@ -13,6 +13,7 @@ extern void __set_page_owner(struct page *page, extern gfp_t __get_page_owner_gfp(struct page *page); extern void __copy_page_owner(struct page *oldpage, struct page *newpage); extern void __set_page_owner_migrate_reason(struct page *page, int reason); +extern void __dump_page_owner(struct page *page); static inline void reset_page_owner(struct page *page, unsigned int order) { @@ -44,6 +45,11 @@ static inline void set_page_owner_migrate_reason(struct page *page, int reason) if (static_branch_unlikely(&page_owner_inited)) __set_page_owner_migrate_reason(page, reason); } +static inline void dump_page_owner(struct page *page) +{ + if (static_branch_unlikely(&page_owner_inited)) + __dump_page_owner(page); +} #else static inline void reset_page_owner(struct page *page, unsigned int order) { @@ -62,5 +68,8 @@ static inline void copy_page_owner(struct page *oldpage, struct page *newpage) static inline void set_page_owner_migrate_reason(struct page *page, int reason) { } +static inline void dump_page_owner(struct page *page) +{ +} #endif /* CONFIG_PAGE_OWNER */ #endif /* __LINUX_PAGE_OWNER_H */ diff --git a/mm/debug.c b/mm/debug.c index 78dc54877075..61b1f1bb328e 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -11,6 +11,7 @@ #include #include #include +#include #include "internal.h" @@ -67,6 +68,7 @@ void dump_page_badflags(struct page *page, const char *reason, void dump_page(struct page *page, const char *reason) { dump_page_badflags(page, reason, 0); + dump_page_owner(page); } EXPORT_SYMBOL(dump_page); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 030fafccaa6b..d98672d33752 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -443,6 +443,7 @@ static void bad_page(struct page *page, const char *reason, printk(KERN_ALERT "BUG: Bad page state in process %s pfn:%05lx\n", current->comm, page_to_pfn(page)); dump_page_badflags(page, reason, bad_flags); + dump_page_owner(page); print_modules(); dump_stack(); diff --git a/mm/page_owner.c b/mm/page_owner.c index a57068cfe52f..44ad1f00c4e1 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -183,6 +183,31 @@ err: return -ENOMEM; } +void __dump_page_owner(struct page *page) +{ + struct page_ext *page_ext = lookup_page_ext(page); + struct stack_trace trace = { + .nr_entries = page_ext->nr_entries, + .entries = &page_ext->trace_entries[0], + }; + gfp_t gfp_mask = page_ext->gfp_mask; + int mt = gfpflags_to_migratetype(gfp_mask); + + if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) { + pr_alert("page_owner info is not active (free page?)\n"); + return; + } + + pr_alert("page allocated via order %u, migratetype %s, " + "gfp_mask %#x(%pGg)\n", page_ext->order, + migratetype_names[mt], gfp_mask, &gfp_mask); + print_stack_trace(&trace, 0); + + if (page_ext->last_migrate_reason != -1) + pr_alert("page has been migrated, last migrate reason: %s\n", + migrate_reason_names[page_ext->last_migrate_reason]); +} + static ssize_t read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) { -- 2.20.1