ddc4a48797
CMA allocation can fail by temporal page refcount increasement by get_page API as well as get_user_pages friends. However, since get_page is one of the most hot function, it is hard to hook get_page to get callstack everytime due to performance concern. Furthermore, get_page could be nested multiple times so we couldn't track all of the pin sites on limited space of page_pinner. Thus, here approach is keep tracking of put_page callsite rather than get_page once VM found the page migration failed. It's based on assumption: 1. Since it's temporal page refcount, it could be released soon before overflowing dmesg log buffer 2. developer can find the pair of get_page by reviewing put_page. By default, it's eanbled. If you want to disable it: echo 0 > $debugfs/page_pinner/failure_tracking You can capture the tracking using: cat $debugfs/page_pinner/alloc_contig_failed note: the example below is artificial: Page pinned ts 386067292 us count 0 PFN 10162530 Block 9924 type Isolate Flags 0x800000000008000c(uptodate|dirty|swapbacked) __page_pinner_migration_failed+0x30/0x104 putback_lru_page+0x90/0xac putback_movable_pages+0xc4/0x204 __alloc_contig_migrate_range+0x290/0x31c alloc_contig_range+0x114/0x2bc cma_alloc+0x2d8/0x698 cma_alloc_write+0x58/0xb8 simple_attr_write+0xd4/0x124 debugfs_attr_write+0x50/0xd8 full_proxy_write+0x70/0xf8 vfs_write+0x168/0x3a8 ksys_write+0x7c/0xec __arm64_sys_write+0x20/0x30 el0_svc_common+0xa4/0x180 do_el0_svc+0x28/0x88 el0_svc+0x14/0x24 Page pinned ts 385867394 us count 0 PFN 10162530 Block 9924 type Isolate Flags 0x800000000008000c(uptodate|dirty|swapbacked) __page_pinner_migration_failed+0x30/0x104 __alloc_contig_migrate_range+0x200/0x31c alloc_contig_range+0x114/0x2bc cma_alloc+0x2d8/0x698 cma_alloc_write+0x58/0xb8 simple_attr_write+0xd4/0x124 debugfs_attr_write+0x50/0xd8 full_proxy_write+0x70/0xf8 vfs_write+0x168/0x3a8 ksys_write+0x7c/0xec __arm64_sys_write+0x20/0x30 el0_svc_common+0xa4/0x180 do_el0_svc+0x28/0x88 el0_svc+0x14/0x24 el0_sync_handler+0x88/0xec el0_sync+0x198/0x1c0 Bug: 183414571 Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Minchan Kim <minchan@google.com> Change-Id: Ie79902c18390eb9f320d823839bb9d9a7fdcdb31
90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_PAGE_EXT_H
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#define __LINUX_PAGE_EXT_H
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#include <linux/types.h>
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#include <linux/stacktrace.h>
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#include <linux/stackdepot.h>
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struct pglist_data;
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struct page_ext_operations {
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size_t offset;
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size_t size;
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bool (*need)(void);
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void (*init)(void);
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};
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#ifdef CONFIG_PAGE_EXTENSION
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enum page_ext_flags {
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PAGE_EXT_OWNER,
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PAGE_EXT_OWNER_ALLOCATED,
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#if defined(CONFIG_PAGE_PINNER)
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/* page refcount was increased by GUP or follow_page(FOLL_GET) */
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PAGE_EXT_GET,
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/* page migration failed */
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PAGE_EXT_PINNER_MIGRATION_FAILED,
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#endif
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#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
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PAGE_EXT_YOUNG,
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PAGE_EXT_IDLE,
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#endif
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};
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/*
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* Page Extension can be considered as an extended mem_map.
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* A page_ext page is associated with every page descriptor. The
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* page_ext helps us add more information about the page.
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* All page_ext are allocated at boot or memory hotplug event,
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* then the page_ext for pfn always exists.
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*/
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struct page_ext {
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unsigned long flags;
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};
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extern unsigned long page_ext_size;
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extern void pgdat_page_ext_init(struct pglist_data *pgdat);
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#ifdef CONFIG_SPARSEMEM
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static inline void page_ext_init_flatmem(void)
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{
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}
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extern void page_ext_init(void);
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#else
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extern void page_ext_init_flatmem(void);
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static inline void page_ext_init(void)
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{
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}
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#endif
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struct page_ext *lookup_page_ext(const struct page *page);
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static inline struct page_ext *page_ext_next(struct page_ext *curr)
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{
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void *next = curr;
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next += page_ext_size;
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return next;
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}
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#else /* !CONFIG_PAGE_EXTENSION */
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struct page_ext;
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static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
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{
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}
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static inline struct page_ext *lookup_page_ext(const struct page *page)
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{
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return NULL;
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}
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static inline void page_ext_init(void)
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{
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}
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static inline void page_ext_init_flatmem(void)
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{
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}
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#endif /* CONFIG_PAGE_EXTENSION */
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#endif /* __LINUX_PAGE_EXT_H */
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