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5e322beefc
Christian Borntraeger reports: With commit8ea1d2a198("mm, frontswap: convert frontswap_enabled to static key") kmemleak complains about a memory leak in swapon unreferenced object 0x3e09ba56000 (size 32112640): comm "swapon", pid 7852, jiffies 4294968787 (age 1490.770s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: __vmalloc_node_range+0x194/0x2d8 vzalloc+0x58/0x68 SyS_swapon+0xd60/0x12f8 system_call+0xd6/0x270 Turns out kmemleak is right. We now allocate the frontswap map depending on the kernel config (and no longer on the enablement) swapfile.c: [...] if (IS_ENABLED(CONFIG_FRONTSWAP)) frontswap_map = vzalloc(BITS_TO_LONGS(maxpages) * sizeof(long)); but later on this is passed along --> enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map); and ignored if frontswap is disabled --> frontswap_init(p->type, frontswap_map); static inline void frontswap_init(unsigned type, unsigned long *map) { if (frontswap_enabled()) __frontswap_init(type, map); } Thing is, that frontswap map is never freed. The leakage is relatively not that bad, because swapon is an infrequent and privileged operation. However, if the first frontswap backend is registered after a swap type has been already enabled, it will WARN_ON in frontswap_register_ops() and frontswap will not be available for the swap type. Fix this by making sure the map is assigned by frontswap_init() as long as CONFIG_FRONTSWAP is enabled. Fixes:8ea1d2a198("mm, frontswap: convert frontswap_enabled to static key") Link: http://lkml.kernel.org/r/20161026134220.2566-1-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
115 lines
2.8 KiB
C
115 lines
2.8 KiB
C
#ifndef _LINUX_FRONTSWAP_H
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#define _LINUX_FRONTSWAP_H
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#include <linux/swap.h>
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#include <linux/mm.h>
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#include <linux/bitops.h>
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#include <linux/jump_label.h>
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struct frontswap_ops {
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void (*init)(unsigned); /* this swap type was just swapon'ed */
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int (*store)(unsigned, pgoff_t, struct page *); /* store a page */
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int (*load)(unsigned, pgoff_t, struct page *); /* load a page */
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void (*invalidate_page)(unsigned, pgoff_t); /* page no longer needed */
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void (*invalidate_area)(unsigned); /* swap type just swapoff'ed */
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struct frontswap_ops *next; /* private pointer to next ops */
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};
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extern void frontswap_register_ops(struct frontswap_ops *ops);
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extern void frontswap_shrink(unsigned long);
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extern unsigned long frontswap_curr_pages(void);
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extern void frontswap_writethrough(bool);
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#define FRONTSWAP_HAS_EXCLUSIVE_GETS
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extern void frontswap_tmem_exclusive_gets(bool);
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extern bool __frontswap_test(struct swap_info_struct *, pgoff_t);
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extern void __frontswap_init(unsigned type, unsigned long *map);
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extern int __frontswap_store(struct page *page);
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extern int __frontswap_load(struct page *page);
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extern void __frontswap_invalidate_page(unsigned, pgoff_t);
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extern void __frontswap_invalidate_area(unsigned);
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#ifdef CONFIG_FRONTSWAP
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extern struct static_key_false frontswap_enabled_key;
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static inline bool frontswap_enabled(void)
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{
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return static_branch_unlikely(&frontswap_enabled_key);
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}
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static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
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{
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return __frontswap_test(sis, offset);
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}
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static inline void frontswap_map_set(struct swap_info_struct *p,
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unsigned long *map)
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{
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p->frontswap_map = map;
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}
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static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
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{
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return p->frontswap_map;
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}
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#else
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/* all inline routines become no-ops and all externs are ignored */
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static inline bool frontswap_enabled(void)
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{
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return false;
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}
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static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
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{
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return false;
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}
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static inline void frontswap_map_set(struct swap_info_struct *p,
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unsigned long *map)
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{
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}
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static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
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{
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return NULL;
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}
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#endif
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static inline int frontswap_store(struct page *page)
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{
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if (frontswap_enabled())
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return __frontswap_store(page);
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return -1;
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}
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static inline int frontswap_load(struct page *page)
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{
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if (frontswap_enabled())
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return __frontswap_load(page);
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return -1;
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}
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static inline void frontswap_invalidate_page(unsigned type, pgoff_t offset)
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{
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if (frontswap_enabled())
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__frontswap_invalidate_page(type, offset);
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}
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static inline void frontswap_invalidate_area(unsigned type)
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{
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if (frontswap_enabled())
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__frontswap_invalidate_area(type);
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}
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static inline void frontswap_init(unsigned type, unsigned long *map)
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{
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#ifdef CONFIG_FRONTSWAP
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__frontswap_init(type, map);
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#endif
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}
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#endif /* _LINUX_FRONTSWAP_H */
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