Date: Mon, 3 Jun 2013 01:22:54 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r251280 - head/sys/vm Message-ID: <201306030122.r531MsuG039456@svn.freebsd.org>
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Author: alc Date: Mon Jun 3 01:22:54 2013 New Revision: 251280 URL: http://svnweb.freebsd.org/changeset/base/251280 Log: Require that the page lock is held, instead of the object lock, when clearing the page's PGA_REFERENCED flag. Since we are typically manipulating the page's act_count field when we are clearing its PGA_REFERENCED flag, the page lock is already held everywhere that we clear the PGA_REFERENCED flag. So, in fact, this revision only changes some comments and an assertion. Nonetheless, it will enable later changes to object locking in the pageout code. Introduce vm_page_assert_locked(), which completely hides the implementation details of the page lock from the caller, and use it in vm_page_aflag_clear(). (The existing vm_page_lock_assert() could not be used in vm_page_aflag_clear().) Over the coming weeks, I expect that we'll either eliminate or replace the various uses of vm_page_lock_assert() with vm_page_assert_locked(). Reviewed by: attilio Sponsored by: EMC / Isilon Storage Division Modified: head/sys/vm/vm_page.c head/sys/vm/vm_page.h Modified: head/sys/vm/vm_page.c ============================================================================== --- head/sys/vm/vm_page.c Sun Jun 2 23:56:38 2013 (r251279) +++ head/sys/vm/vm_page.c Mon Jun 3 01:22:54 2013 (r251280) @@ -2725,6 +2725,13 @@ vm_page_trylock_KBI(vm_page_t m, const c #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) void +vm_page_assert_locked_KBI(vm_page_t m, const char *file, int line) +{ + + vm_page_lock_assert_KBI(m, MA_OWNED, file, line); +} + +void vm_page_lock_assert_KBI(vm_page_t m, int a, const char *file, int line) { Modified: head/sys/vm/vm_page.h ============================================================================== --- head/sys/vm/vm_page.h Sun Jun 2 23:56:38 2013 (r251279) +++ head/sys/vm/vm_page.h Mon Jun 3 01:22:54 2013 (r251280) @@ -229,9 +229,12 @@ extern struct mtx_padalign pa_lock[]; #define vm_page_trylock(m) mtx_trylock(vm_page_lockptr((m))) #endif #if defined(INVARIANTS) +#define vm_page_assert_locked(m) \ + vm_page_assert_locked_KBI((m), __FILE__, __LINE__) #define vm_page_lock_assert(m, a) \ vm_page_lock_assert_KBI((m), (a), __FILE__, __LINE__) #else +#define vm_page_assert_locked(m) #define vm_page_lock_assert(m, a) #endif @@ -240,10 +243,9 @@ extern struct mtx_padalign pa_lock[]; * these flags, the functions vm_page_aflag_set() and vm_page_aflag_clear() * must be used. Neither these flags nor these functions are part of the KBI. * - * PGA_REFERENCED may be cleared only if the object containing the page is - * locked. It is set by both the MI and MD VM layers. However, kernel - * loadable modules should not directly set this flag. They should call - * vm_page_reference() instead. + * PGA_REFERENCED may be cleared only if the page is locked. It is set by + * both the MI and MD VM layers. However, kernel loadable modules should not + * directly set this flag. They should call vm_page_reference() instead. * * PGA_WRITEABLE is set exclusively on managed pages by pmap_enter(). When it * does so, the page must be VPO_BUSY. The MI VM layer must never access this @@ -424,6 +426,7 @@ void vm_page_lock_KBI(vm_page_t m, const void vm_page_unlock_KBI(vm_page_t m, const char *file, int line); int vm_page_trylock_KBI(vm_page_t m, const char *file, int line); #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) +void vm_page_assert_locked_KBI(vm_page_t m, const char *file, int line); void vm_page_lock_assert_KBI(vm_page_t m, int a, const char *file, int line); #endif @@ -451,11 +454,10 @@ vm_page_aflag_clear(vm_page_t m, uint8_t uint32_t *addr, val; /* - * The PGA_REFERENCED flag can only be cleared if the object - * containing the page is locked. + * The PGA_REFERENCED flag can only be cleared if the page is locked. */ if ((bits & PGA_REFERENCED) != 0) - VM_PAGE_OBJECT_LOCK_ASSERT(m); + vm_page_assert_locked(m); /* * Access the whole 32-bit word containing the aflags field with an
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