Makes dept able to track PG_locked waits and events, which will be useful in practice. See the following link that shows dept worked with PG_locked and detected real issues in practice:
https://lore.kernel.org/lkml/1674268856-31807-1-git-send-email-byungchul.par...
Signed-off-by: Byungchul Park byungchul@sk.com --- include/linux/mm_types.h | 2 + include/linux/page-flags.h | 125 +++++++++++++++++++++++++++++++++---- include/linux/pagemap.h | 37 ++++++++++- mm/filemap.c | 34 ++++++++++ mm/mm_init.c | 2 + 5 files changed, 187 insertions(+), 13 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 3b7d05e7169c..42b6959882b3 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -22,6 +22,7 @@ #include <linux/types.h> #include <linux/rseq_types.h> #include <linux/bitmap.h> +#include <linux/dept.h>
#include <asm/mmu.h>
@@ -219,6 +220,7 @@ struct page { struct page *kmsan_shadow; struct page *kmsan_origin; #endif + struct dept_ext_wgen pg_locked_wgen; } _struct_page_alignment;
/* diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index f7a0e4af0c73..8ab39823ea31 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -198,6 +198,61 @@ enum pageflags {
#ifndef __GENERATING_BOUNDS_H
+#ifdef CONFIG_DEPT +#include <linux/kernel.h> +#include <linux/dept.h> + +extern struct dept_map pg_locked_map; + +/* + * Place the following annotations in its suitable point in code: + * + * Annotate dept_page_set_bit() around firstly set_bit*() + * Annotate dept_page_clear_bit() around clear_bit*() + * Annotate dept_page_wait_on_bit() around wait_on_bit*() + */ + +static inline void dept_page_set_bit(struct page *p, int bit_nr) +{ + if (bit_nr == PG_locked) + dept_request_event(&pg_locked_map, &p->pg_locked_wgen); +} + +static inline void dept_page_clear_bit(struct page *p, int bit_nr) +{ + if (bit_nr == PG_locked) + dept_event(&pg_locked_map, 1UL, _RET_IP_, __func__, &p->pg_locked_wgen); +} + +static inline void dept_page_wait_on_bit(struct page *p, int bit_nr) +{ + if (bit_nr == PG_locked) + dept_wait(&pg_locked_map, 1UL, _RET_IP_, __func__, 0, -1L); +} + +static inline void dept_folio_set_bit(struct folio *f, int bit_nr) +{ + dept_page_set_bit(&f->page, bit_nr); +} + +static inline void dept_folio_clear_bit(struct folio *f, int bit_nr) +{ + dept_page_clear_bit(&f->page, bit_nr); +} + +static inline void dept_folio_wait_on_bit(struct folio *f, int bit_nr) +{ + dept_page_wait_on_bit(&f->page, bit_nr); +} +#else +#define dept_page_set_bit(p, bit_nr) do { } while (0) +#define dept_page_clear_bit(p, bit_nr) do { } while (0) +#define dept_page_wait_on_bit(p, bit_nr) do { } while (0) +#define dept_folio_set_bit(f, bit_nr) do { } while (0) +#define dept_folio_clear_bit(f, bit_nr) do { } while (0) +#define dept_folio_wait_on_bit(f, bit_nr) do { } while (0) +#endif + #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);
@@ -419,27 +474,51 @@ static __always_inline bool folio_test_##name(const struct folio *folio) \
#define FOLIO_SET_FLAG(name, page) \ static __always_inline void folio_set_##name(struct folio *folio) \ -{ set_bit(PG_##name, folio_flags(folio, page)); } +{ \ + set_bit(PG_##name, folio_flags(folio, page)); \ + dept_folio_set_bit(folio, PG_##name); \ +}
#define FOLIO_CLEAR_FLAG(name, page) \ static __always_inline void folio_clear_##name(struct folio *folio) \ -{ clear_bit(PG_##name, folio_flags(folio, page)); } +{ \ + clear_bit(PG_##name, folio_flags(folio, page)); \ + dept_folio_clear_bit(folio, PG_##name); \ +}
#define __FOLIO_SET_FLAG(name, page) \ static __always_inline void __folio_set_##name(struct folio *folio) \ -{ __set_bit(PG_##name, folio_flags(folio, page)); } +{ \ + __set_bit(PG_##name, folio_flags(folio, page)); \ + dept_folio_set_bit(folio, PG_##name); \ +}
#define __FOLIO_CLEAR_FLAG(name, page) \ static __always_inline void __folio_clear_##name(struct folio *folio) \ -{ __clear_bit(PG_##name, folio_flags(folio, page)); } +{ \ + __clear_bit(PG_##name, folio_flags(folio, page)); \ + dept_folio_clear_bit(folio, PG_##name); \ +}
#define FOLIO_TEST_SET_FLAG(name, page) \ static __always_inline bool folio_test_set_##name(struct folio *folio) \ -{ return test_and_set_bit(PG_##name, folio_flags(folio, page)); } +{ \ + bool __ret = test_and_set_bit(PG_##name, folio_flags(folio, page)); \ + \ + if (!__ret) \ + dept_folio_set_bit(folio, PG_##name); \ + return __ret; \ +}
#define FOLIO_TEST_CLEAR_FLAG(name, page) \ static __always_inline bool folio_test_clear_##name(struct folio *folio) \ -{ return test_and_clear_bit(PG_##name, folio_flags(folio, page)); } +{ \ + bool __ret = test_and_clear_bit(PG_##name, folio_flags(folio, page)); \ + \ + if (__ret) \ + dept_folio_clear_bit(folio, PG_##name); \ + return __ret; \ +}
#define FOLIO_FLAG(name, page) \ FOLIO_TEST_FLAG(name, page) \ @@ -454,32 +533,54 @@ static __always_inline int Page##uname(const struct page *page) \ #define SETPAGEFLAG(uname, lname, policy) \ FOLIO_SET_FLAG(lname, FOLIO_##policy) \ static __always_inline void SetPage##uname(struct page *page) \ -{ set_bit(PG_##lname, &policy(page, 1)->flags.f); } +{ \ + set_bit(PG_##lname, &policy(page, 1)->flags.f); \ + dept_page_set_bit(page, PG_##lname); \ +}
#define CLEARPAGEFLAG(uname, lname, policy) \ FOLIO_CLEAR_FLAG(lname, FOLIO_##policy) \ static __always_inline void ClearPage##uname(struct page *page) \ -{ clear_bit(PG_##lname, &policy(page, 1)->flags.f); } +{ \ + clear_bit(PG_##lname, &policy(page, 1)->flags.f); \ + dept_page_clear_bit(page, PG_##lname); \ +}
#define __SETPAGEFLAG(uname, lname, policy) \ __FOLIO_SET_FLAG(lname, FOLIO_##policy) \ static __always_inline void __SetPage##uname(struct page *page) \ -{ __set_bit(PG_##lname, &policy(page, 1)->flags.f); } +{ \ + __set_bit(PG_##lname, &policy(page, 1)->flags.f); \ + dept_page_set_bit(page, PG_##lname); \ +}
#define __CLEARPAGEFLAG(uname, lname, policy) \ __FOLIO_CLEAR_FLAG(lname, FOLIO_##policy) \ static __always_inline void __ClearPage##uname(struct page *page) \ -{ __clear_bit(PG_##lname, &policy(page, 1)->flags.f); } +{ \ + __clear_bit(PG_##lname, &policy(page, 1)->flags.f); \ + dept_page_clear_bit(page, PG_##lname); \ +}
#define TESTSETFLAG(uname, lname, policy) \ FOLIO_TEST_SET_FLAG(lname, FOLIO_##policy) \ static __always_inline int TestSetPage##uname(struct page *page) \ -{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags.f); } +{ \ + bool ret = test_and_set_bit(PG_##lname, &policy(page, 1)->flags.f);\ + if (!ret) \ + dept_page_set_bit(page, PG_##lname); \ + return ret; \ +}
#define TESTCLEARFLAG(uname, lname, policy) \ FOLIO_TEST_CLEAR_FLAG(lname, FOLIO_##policy) \ static __always_inline int TestClearPage##uname(struct page *page) \ -{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags.f); } +{ \ + bool ret = test_and_clear_bit(PG_##lname, &policy(page, 1)->flags.f);\ + if (ret) \ + dept_page_clear_bit(page, PG_##lname); \ + return ret; \ +}
#define PAGEFLAG(uname, lname, policy) \ TESTPAGEFLAG(uname, lname, policy) \ diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index e601a3144f28..3abb45c5557c 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1111,7 +1111,12 @@ void folio_unlock(struct folio *folio); */ static inline bool folio_trylock(struct folio *folio) { - return likely(!test_and_set_bit_lock(PG_locked, folio_flags(folio, 0))); + bool ret = !test_and_set_bit_lock(PG_locked, folio_flags(folio, 0)); + + if (ret) + dept_page_set_bit(&folio->page, PG_locked); + + return likely(ret); }
/* @@ -1147,6 +1152,16 @@ static inline bool trylock_page(struct page *page) static inline void folio_lock(struct folio *folio) { might_sleep(); + + /* + * dept_page_wait_on_bit() will be called if __folio_lock() goes + * through a real wait path. However, for better job to detect + * *potential* deadlocks, let's assume that folio_lock() always + * goes through wait so that dept can take into account all the + * potential cases. + */ + dept_page_wait_on_bit(&folio->page, PG_locked); + if (!folio_trylock(folio)) __folio_lock(folio); } @@ -1167,6 +1182,15 @@ static inline void lock_page(struct page *page) struct folio *folio; might_sleep();
+ /* + * dept_page_wait_on_bit() will be called if __folio_lock() goes + * through a real wait path. However, for better job to detect + * *potential* deadlocks, let's assume that lock_page() always + * goes through wait so that dept can take into account all the + * potential cases. + */ + dept_page_wait_on_bit(page, PG_locked); + folio = page_folio(page); if (!folio_trylock(folio)) __folio_lock(folio); @@ -1185,6 +1209,17 @@ static inline void lock_page(struct page *page) static inline int folio_lock_killable(struct folio *folio) { might_sleep(); + + /* + * dept_page_wait_on_bit() will be called if + * __folio_lock_killable() goes through a real wait path. + * However, for better job to detect *potential* deadlocks, + * let's assume that folio_lock_killable() always goes through + * wait so that dept can take into account all the potential + * cases. + */ + dept_page_wait_on_bit(&folio->page, PG_locked); + if (!folio_trylock(folio)) return __folio_lock_killable(folio); return 0; diff --git a/mm/filemap.c b/mm/filemap.c index dfc8a31f1222..d7e567af3261 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -48,6 +48,7 @@ #include <linux/rcupdate_wait.h> #include <linux/sched/mm.h> #include <linux/sysctl.h> +#include <linux/dept.h> #include <asm/pgalloc.h> #include <asm/tlbflush.h> #include "internal.h" @@ -1145,6 +1146,7 @@ static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, if (flags & WQ_FLAG_CUSTOM) { if (test_and_set_bit(key->bit_nr, &key->folio->flags.f)) return -1; + dept_page_set_bit(&key->folio->page, key->bit_nr); flags |= WQ_FLAG_DONE; } } @@ -1185,6 +1187,13 @@ static void folio_wake_bit(struct folio *folio, int bit_nr) key.bit_nr = bit_nr; key.page_match = 0;
+ /* + * dept_page_clear_bit() being called multiple times is harmless. + * The worst case is to miss some dependencies but it's okay. + */ + if (bit_nr == PG_locked) + dept_page_clear_bit(&folio->page, bit_nr); + spin_lock_irqsave(&q->lock, flags); __wake_up_locked_key(q, TASK_NORMAL, &key);
@@ -1228,6 +1237,7 @@ static inline bool folio_trylock_flag(struct folio *folio, int bit_nr, if (wait->flags & WQ_FLAG_EXCLUSIVE) { if (test_and_set_bit(bit_nr, &folio->flags.f)) return false; + dept_page_set_bit(&folio->page, bit_nr); } else if (test_bit(bit_nr, &folio->flags.f)) return false;
@@ -1235,6 +1245,9 @@ static inline bool folio_trylock_flag(struct folio *folio, int bit_nr, return true; }
+struct dept_map __maybe_unused pg_locked_map = DEPT_MAP_INITIALIZER(pg_locked_map, NULL); +EXPORT_SYMBOL(pg_locked_map); + static inline int folio_wait_bit_common(struct folio *folio, int bit_nr, int state, enum behavior behavior) { @@ -1246,6 +1259,8 @@ static inline int folio_wait_bit_common(struct folio *folio, int bit_nr, unsigned long pflags; bool in_thrashing;
+ dept_page_wait_on_bit(&folio->page, bit_nr); + if (bit_nr == PG_locked && !folio_test_uptodate(folio) && folio_test_workingset(folio)) { delayacct_thrashing_start(&in_thrashing); @@ -1339,6 +1354,23 @@ static inline int folio_wait_bit_common(struct folio *folio, int bit_nr, break; }
+ /* + * dept_page_set_bit() might have been called already in + * folio_trylock_flag(), wake_page_function() or somewhere. + * However, call it again to reset the wgen of dept to ensure + * dept_page_wait_on_bit() is called prior to + * dept_page_set_bit(). + * + * Remind dept considers all the waits between + * dept_page_set_bit() and dept_page_clear_bit() as potential + * event disturbers. Ensure the correct sequence so that dept + * can make correct decisions: + * + * wait -> acquire(set bit) -> release(clear bit) + */ + if (wait->flags & WQ_FLAG_DONE) + dept_page_set_bit(&folio->page, bit_nr); + /* * If a signal happened, this 'finish_wait()' may remove the last * waiter from the wait-queues, but the folio waiters bit will remain @@ -1496,6 +1528,7 @@ void folio_unlock(struct folio *folio) BUILD_BUG_ON(PG_waiters != 7); BUILD_BUG_ON(PG_locked > 7); VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); + dept_page_clear_bit(&folio->page, PG_locked); if (folio_xor_flags_has_waiters(folio, 1 << PG_locked)) folio_wake_bit(folio, PG_locked); } @@ -1526,6 +1559,7 @@ void folio_end_read(struct folio *folio, bool success)
if (likely(success)) mask |= 1 << PG_uptodate; + dept_page_clear_bit(&folio->page, PG_locked); if (folio_xor_flags_has_waiters(folio, mask)) folio_wake_bit(folio, PG_locked); } diff --git a/mm/mm_init.c b/mm/mm_init.c index 7712d887b696..f1d3e4afd43b 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -32,6 +32,7 @@ #include <linux/vmstat.h> #include <linux/kexec_handover.h> #include <linux/hugetlb.h> +#include <linux/dept.h> #include "internal.h" #include "slab.h" #include "shuffle.h" @@ -587,6 +588,7 @@ void __meminit __init_single_page(struct page *page, unsigned long pfn, atomic_set(&page->_mapcount, -1); page_cpupid_reset_last(page); page_kasan_tag_reset(page); + dept_ext_wgen_init(&page->pg_locked_wgen);
INIT_LIST_HEAD(&page->lru); #ifdef WANT_PAGE_VIRTUAL