Commit d9ee35ac authored Jun 12, 2017 by Vlastimil Babka Committed by Ingo Molnar Jun 13, 2017

x86/mm: Disable 1GB direct mappings when disabling 2MB mappings



The kmemleak and debug_pagealloc features both disable using huge pages for
direct mappings so they can do cpa() on page level granularity in any context.

However they only do that for 2MB pages, which means 1GB pages can still be
used if the CPU supports it, unless disabled by a boot param, which is
non-obvious. Disable also 1GB pages when disabling 2MB pages.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/2be70c78-6130-855d-3dfa-d87bd1dd4fda@suse.cz


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 8a524f80

arch/x86/mm/init.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -161,16 +161,16 @@ static int page_size_mask;

		static void __init probe_page_size_mask(void)
		{
		#if !defined(CONFIG_KMEMCHECK)
		/*
		* For CONFIG_KMEMCHECK or pagealloc debugging, identity mapping will
		* use small pages.
		* This will simplify cpa(), which otherwise needs to support splitting
		* large pages into small in interrupt context, etc.
		*/
		if (boot_cpu_has(X86_FEATURE_PSE) && !debug_pagealloc_enabled())
		if (boot_cpu_has(X86_FEATURE_PSE) && !debug_pagealloc_enabled() && !IS_ENABLED(CONFIG_KMEMCHECK))
		page_size_mask \|= 1 << PG_LEVEL_2M;
		#endif
		else
		direct_gbpages = 0;

		/* Enable PSE if available */
		if (boot_cpu_has(X86_FEATURE_PSE))

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