mm/frontswap: mark various intentional data races

Qian Cai · torvalds · commit 96bdd2bcc1a7 · 2020-08-14T19:56:56.000-07:00
There are a few information counters that are intentionally not protected against increment races, so just annotate them using the data_race() macro. BUG: KCSAN: data-race in __frontswap_store / __frontswap_store write to 0xffffffff8b7174d8 of 8 bytes by task 6396 on cpu 103: __frontswap_store+0x2d0/0x344 inc_frontswap_failed_stores at mm/frontswap.c:70 (inlined by) __frontswap_store at mm/frontswap.c:280 swap_writepage+0x83/0xf0 pageout+0x33e/0xae0 shrink_page_list+0x1f57/0x2870 shrink_inactive_list+0x316/0x880 shrink_lruvec+0x8dc/0x1380 shrink_node+0x317/0xd80 do_try_to_free_pages+0x1f7/0xa10 try_to_free_pages+0x26c/0x5e0 __alloc_pages_slowpath+0x458/0x1290 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x170/0x700 __handle_mm_fault+0xc9f/0xd00 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 read to 0xffffffff8b7174d8 of 8 bytes by task 6405 on cpu 47: __frontswap_store+0x2b9/0x344 inc_frontswap_failed_stores at mm/frontswap.c:70 (inlined by) __frontswap_store at mm/frontswap.c:280 swap_writepage+0x83/0xf0 pageout+0x33e/0xae0 shrink_page_list+0x1f57/0x2870 shrink_inactive_list+0x316/0x880 shrink_lruvec+0x8dc/0x1380 shrink_node+0x317/0xd80 do_try_to_free_pages+0x1f7/0xa10 try_to_free_pages+0x26c/0x5e0 __alloc_pages_slowpath+0x458/0x1290 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x170/0x700 __handle_mm_fault+0xc9f/0xd00 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Marco Elver <elver@google.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Link: http://lkml.kernel.org/r/1581114499-5042-1-git-send-email-cai@lca.pw Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/frontswap.c b/mm/frontswap.c
@@ -61,16 +61,16 @@ static u64 frontswap_failed_stores;
 static u64 frontswap_invalidates;
 
 static inline void inc_frontswap_loads(void) {
-	frontswap_loads++;
+	data_race(frontswap_loads++);
 }
 static inline void inc_frontswap_succ_stores(void) {
-	frontswap_succ_stores++;
+	data_race(frontswap_succ_stores++);
 }
 static inline void inc_frontswap_failed_stores(void) {
-	frontswap_failed_stores++;
+	data_race(frontswap_failed_stores++);
 }
 static inline void inc_frontswap_invalidates(void) {
-	frontswap_invalidates++;
+	data_race(frontswap_invalidates++);
 }
 #else
 static inline void inc_frontswap_loads(void) { }

Original file line number	Diff line number	Diff line change
`@@ -61,16 +61,16 @@ static u64 frontswap_failed_stores;`
`61`	`61`	`static u64 frontswap_invalidates;`
`62`	`62`
`63`	`63`	`static inline void inc_frontswap_loads(void) {`
`64`		`- frontswap_loads++;`
	`64`	`+ data_race(frontswap_loads++);`
`65`	`65`	`}`
`66`	`66`	`static inline void inc_frontswap_succ_stores(void) {`
`67`		`- frontswap_succ_stores++;`
	`67`	`+ data_race(frontswap_succ_stores++);`
`68`	`68`	`}`
`69`	`69`	`static inline void inc_frontswap_failed_stores(void) {`
`70`		`- frontswap_failed_stores++;`
	`70`	`+ data_race(frontswap_failed_stores++);`
`71`	`71`	`}`
`72`	`72`	`static inline void inc_frontswap_invalidates(void) {`
`73`		`- frontswap_invalidates++;`
	`73`	`+ data_race(frontswap_invalidates++);`
`74`	`74`	`}`
`75`	`75`	`#else`
`76`	`76`	`static inline void inc_frontswap_loads(void) { }`