Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752434AbdHGHQL (ORCPT ); Mon, 7 Aug 2017 03:16:11 -0400 Received: from LGEAMRELO12.lge.com ([156.147.23.52]:41750 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752103AbdHGHON (ORCPT ); Mon, 7 Aug 2017 03:14:13 -0400 X-Original-SENDERIP: 156.147.1.126 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com From: Byungchul Park To: peterz@infradead.org, mingo@kernel.org Cc: tglx@linutronix.de, walken@google.com, boqun.feng@gmail.com, kirill@shutemov.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, willy@infradead.org, npiggin@gmail.com, kernel-team@lge.com Subject: [PATCH v8 11/14] lockdep: Apply crossrelease to PG_locked locks Date: Mon, 7 Aug 2017 16:12:58 +0900 Message-Id: <1502089981-21272-12-git-send-email-byungchul.park@lge.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1502089981-21272-1-git-send-email-byungchul.park@lge.com> References: <1502089981-21272-1-git-send-email-byungchul.park@lge.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7220 Lines: 251 Although lock_page() and its family can cause deadlock, the lock correctness validator could not be applied to them until now, becasue things like unlock_page() might be called in a different context from the acquisition context, which violates lockdep's assumption. Thanks to CONFIG_LOCKDEP_CROSSRELEASE, we can now apply the lockdep detector to page locks. Applied it. Signed-off-by: Byungchul Park --- include/linux/mm_types.h | 8 ++++ include/linux/pagemap.h | 101 ++++++++++++++++++++++++++++++++++++++++++++--- lib/Kconfig.debug | 8 ++++ mm/filemap.c | 4 +- mm/page_alloc.c | 3 ++ 5 files changed, 116 insertions(+), 8 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index ff15181..f1e3dba 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -16,6 +16,10 @@ #include +#ifdef CONFIG_LOCKDEP_PAGELOCK +#include +#endif + #ifndef AT_VECTOR_SIZE_ARCH #define AT_VECTOR_SIZE_ARCH 0 #endif @@ -216,6 +220,10 @@ struct page { #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS int _last_cpupid; #endif + +#ifdef CONFIG_LOCKDEP_PAGELOCK + struct lockdep_map_cross map; +#endif } /* * The struct page can be forced to be double word aligned so that atomic ops diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 9717ca8..9f448c6 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -14,6 +14,9 @@ #include #include /* for in_interrupt() */ #include +#ifdef CONFIG_LOCKDEP_PAGELOCK +#include +#endif /* * Bits in mapping->flags. @@ -450,26 +453,91 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma, return pgoff; } +#ifdef CONFIG_LOCKDEP_PAGELOCK +#define lock_page_init(p) \ +do { \ + static struct lock_class_key __key; \ + lockdep_init_map_crosslock((struct lockdep_map *)&(p)->map, \ + "(PG_locked)" #p, &__key, 0); \ +} while (0) + +static inline void lock_page_acquire(struct page *page, int try) +{ + page = compound_head(page); + lock_acquire_exclusive((struct lockdep_map *)&page->map, 0, + try, NULL, _RET_IP_); +} + +static inline void lock_page_release(struct page *page) +{ + page = compound_head(page); + /* + * lock_commit_crosslock() is necessary for crosslocks. + */ + lock_commit_crosslock((struct lockdep_map *)&page->map); + lock_release((struct lockdep_map *)&page->map, 0, _RET_IP_); +} +#else +static inline void lock_page_init(struct page *page) {} +static inline void lock_page_free(struct page *page) {} +static inline void lock_page_acquire(struct page *page, int try) {} +static inline void lock_page_release(struct page *page) {} +#endif + extern void __lock_page(struct page *page); extern int __lock_page_killable(struct page *page); extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm, unsigned int flags); -extern void unlock_page(struct page *page); +extern void do_raw_unlock_page(struct page *page); -static inline int trylock_page(struct page *page) +static inline void unlock_page(struct page *page) +{ + lock_page_release(page); + do_raw_unlock_page(page); +} + +static inline int do_raw_trylock_page(struct page *page) { page = compound_head(page); return (likely(!test_and_set_bit_lock(PG_locked, &page->flags))); } +static inline int trylock_page(struct page *page) +{ + if (do_raw_trylock_page(page)) { + lock_page_acquire(page, 1); + return 1; + } + return 0; +} + /* * lock_page may only be called if we have the page's inode pinned. */ static inline void lock_page(struct page *page) { might_sleep(); - if (!trylock_page(page)) + + if (!do_raw_trylock_page(page)) __lock_page(page); + /* + * acquire() must be after actual lock operation for crosslocks. + * This way a crosslock and current lock can be ordered like: + * + * CONTEXT 1 CONTEXT 2 + * --------- --------- + * lock A (cross) + * acquire A + * X = atomic_inc_return(&cross_gen_id) + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + * acquire B + * Y = atomic_read_acquire(&cross_gen_id) + * lock B + * + * so that 'lock A and then lock B' can be seen globally, + * if X <= Y. + */ + lock_page_acquire(page, 0); } /* @@ -479,9 +547,20 @@ static inline void lock_page(struct page *page) */ static inline int lock_page_killable(struct page *page) { + int ret; + might_sleep(); - if (!trylock_page(page)) - return __lock_page_killable(page); + + if (!do_raw_trylock_page(page)) { + ret = __lock_page_killable(page); + if (ret) + return ret; + } + /* + * acquire() must be after actual lock operation for crosslocks. + * This way a crosslock and other locks can be ordered. + */ + lock_page_acquire(page, 0); return 0; } @@ -496,7 +575,17 @@ static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm, unsigned int flags) { might_sleep(); - return trylock_page(page) || __lock_page_or_retry(page, mm, flags); + + if (do_raw_trylock_page(page) || __lock_page_or_retry(page, mm, flags)) { + /* + * acquire() must be after actual lock operation for crosslocks. + * This way a crosslock and other locks can be ordered. + */ + lock_page_acquire(page, 0); + return 1; + } + + return 0; } /* diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 4ba8adc..99b5f76 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1093,6 +1093,14 @@ config LOCKDEP_COMPLETE A deadlock caused by wait_for_completion() and complete() can be detected by lockdep using crossrelease feature. +config LOCKDEP_PAGELOCK + bool "Lock debugging: allow PG_locked lock to use deadlock detector" + select LOCKDEP_CROSSRELEASE + default n + help + PG_locked lock is a kind of crosslock. Using crossrelease feature, + PG_locked lock can work with runtime deadlock detector. + config PROVE_LOCKING bool "Lock debugging: prove locking correctness" depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT diff --git a/mm/filemap.c b/mm/filemap.c index a497024..0d83bf0 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1083,7 +1083,7 @@ static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem * portably (architectures that do LL/SC can test any bit, while x86 can * test the sign bit). */ -void unlock_page(struct page *page) +void do_raw_unlock_page(struct page *page) { BUILD_BUG_ON(PG_waiters != 7); page = compound_head(page); @@ -1091,7 +1091,7 @@ void unlock_page(struct page *page) if (clear_bit_unlock_is_negative_byte(PG_locked, &page->flags)) wake_up_page_bit(page, PG_locked); } -EXPORT_SYMBOL(unlock_page); +EXPORT_SYMBOL(do_raw_unlock_page); /** * end_page_writeback - end writeback against a page diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6d30e91..2cbf412 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5406,6 +5406,9 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, } else { __init_single_pfn(pfn, zone, nid); } +#ifdef CONFIG_LOCKDEP_PAGELOCK + lock_page_init(pfn_to_page(pfn)); +#endif } } -- 1.9.1