From 67350a5c4514c280665cdb45439d32a008a264ba Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 25 Jun 2008 00:19:11 -0400 Subject: [PATCH] x86: simplify vmalloc_sync_all vmalloc_sync_all() is only called from register_die_notifier and alloc_vm_area. Neither is on any performance-critical paths, so vmalloc_sync_all() itself is not on any hot paths. Given that the optimisations in vmalloc_sync_all add a fair amount of code and complexity, and are fairly hard to evaluate for correctness, it's better to just remove them to simplify the code rather than worry about its absolute performance. Signed-off-by: Jeremy Fitzhardinge Cc: xen-devel Cc: Stephen Tweedie Cc: Eduardo Habkost Cc: Mark McLoughlin Signed-off-by: Ingo Molnar --- arch/x86/mm/fault.c | 77 ++++++++++++++++++----------------------------------- 1 file changed, 26 insertions(+), 51 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 578b768..d0f5fce 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -903,14 +903,7 @@ LIST_HEAD(pgd_list); void vmalloc_sync_all(void) { #ifdef CONFIG_X86_32 - /* - * Note that races in the updates of insync and start aren't - * problematic: insync can only get set bits added, and updates to - * start are only improving performance (without affecting correctness - * if undone). - */ - static DECLARE_BITMAP(insync, PTRS_PER_PGD); - static unsigned long start = TASK_SIZE; + unsigned long start = VMALLOC_START & PGDIR_MASK; unsigned long address; if (SHARED_KERNEL_PMD) @@ -918,56 +911,38 @@ void vmalloc_sync_all(void) BUILD_BUG_ON(TASK_SIZE & ~PGDIR_MASK); for (address = start; address >= TASK_SIZE; address += PGDIR_SIZE) { - if (!test_bit(pgd_index(address), insync)) { - unsigned long flags; - struct page *page; - - spin_lock_irqsave(&pgd_lock, flags); - list_for_each_entry(page, &pgd_list, lru) { - if (!vmalloc_sync_one(page_address(page), - address)) - break; - } - spin_unlock_irqrestore(&pgd_lock, flags); - if (!page) - set_bit(pgd_index(address), insync); + unsigned long flags; + struct page *page; + + spin_lock_irqsave(&pgd_lock, flags); + list_for_each_entry(page, &pgd_list, lru) { + if (!vmalloc_sync_one(page_address(page), + address)) + break; } - if (address == start && test_bit(pgd_index(address), insync)) - start = address + PGDIR_SIZE; + spin_unlock_irqrestore(&pgd_lock, flags); } #else /* CONFIG_X86_64 */ - /* - * Note that races in the updates of insync and start aren't - * problematic: insync can only get set bits added, and updates to - * start are only improving performance (without affecting correctness - * if undone). - */ - static DECLARE_BITMAP(insync, PTRS_PER_PGD); - static unsigned long start = VMALLOC_START & PGDIR_MASK; + unsigned long start = VMALLOC_START & PGDIR_MASK; unsigned long address; for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) { - if (!test_bit(pgd_index(address), insync)) { - const pgd_t *pgd_ref = pgd_offset_k(address); - unsigned long flags; - struct page *page; - - if (pgd_none(*pgd_ref)) - continue; - spin_lock_irqsave(&pgd_lock, flags); - list_for_each_entry(page, &pgd_list, lru) { - pgd_t *pgd; - pgd = (pgd_t *)page_address(page) + pgd_index(address); - if (pgd_none(*pgd)) - set_pgd(pgd, *pgd_ref); - else - BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); - } - spin_unlock_irqrestore(&pgd_lock, flags); - set_bit(pgd_index(address), insync); + const pgd_t *pgd_ref = pgd_offset_k(address); + unsigned long flags; + struct page *page; + + if (pgd_none(*pgd_ref)) + continue; + spin_lock_irqsave(&pgd_lock, flags); + list_for_each_entry(page, &pgd_list, lru) { + pgd_t *pgd; + pgd = (pgd_t *)page_address(page) + pgd_index(address); + if (pgd_none(*pgd)) + set_pgd(pgd, *pgd_ref); + else + BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); } - if (address == start) - start = address + PGDIR_SIZE; + spin_unlock_irqrestore(&pgd_lock, flags); } #endif } -- 2.7.4