Commit 67350a5c authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
Browse files

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: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 15878c0b

arch/x86/mm/fault.c

+26 −51
Original line number Diff line number Diff line
@@ -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)
@@ -918,7 +911,6 @@ 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;
@@ -929,25 +921,12 @@ void vmalloc_sync_all(void) 
				break;

		}

		spin_unlock_irqrestore(&pgd_lock, flags);

			if (!page)

				set_bit(pgd_index(address), insync);

		}

		if (address == start && test_bit(pgd_index(address), insync))

			start = address + PGDIR_SIZE;

	}

#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;
@@ -964,10 +943,6 @@ void vmalloc_sync_all(void) 
				BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));

		}

		spin_unlock_irqrestore(&pgd_lock, flags);

			set_bit(pgd_index(address), insync);

		}

		if (address == start)

			start = address + PGDIR_SIZE;

	}

#endif

}

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