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Commit ec11408a authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Linus Torvalds
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mm/large system hash: use vmalloc for size > MAX_ORDER when !hashdist 

The kernel currently clamps large system hashes to MAX_ORDER when hashdist
is not set, which is rather arbitrary.

vmalloc space is limited on 32-bit machines, but this shouldn't result in
much more used because of small physical memory limiting system hash
sizes.

Include "vmalloc" or "linear" in the kernel log message.

Link: http://lkml.kernel.org/r/20190605144814.29319-1-npiggin@gmail.com


Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d9009d67

mm/page_alloc.c

+9 −7
Original line number Diff line number Diff line
@@ -7981,6 +7981,7 @@ void *__init alloc_large_system_hash(const char *tablename, 
	unsigned long log2qty, size;

	void *table = NULL;

	gfp_t gfp_flags;

	bool virt;



	/* allow the kernel cmdline to have a say */

	if (!numentries) {
@@ -8037,6 +8038,7 @@ void *__init alloc_large_system_hash(const char *tablename, 


	gfp_flags = (flags & HASH_ZERO) ? GFP_ATOMIC | __GFP_ZERO : GFP_ATOMIC;

	do {

		virt = false;

		size = bucketsize << log2qty;

		if (flags & HASH_EARLY) {

			if (flags & HASH_ZERO)
@@ -8044,26 +8046,26 @@ void *__init alloc_large_system_hash(const char *tablename, 
			else

				table = memblock_alloc_raw(size,

							   SMP_CACHE_BYTES);

		} else if (hashdist) {

		} else if (get_order(size) >= MAX_ORDER || hashdist) {

			table = __vmalloc(size, gfp_flags, PAGE_KERNEL);

			virt = true;

		} else {

			/*

			 * If bucketsize is not a power-of-two, we may free

			 * some pages at the end of hash table which

			 * alloc_pages_exact() automatically does

			 */

			if (get_order(size) < MAX_ORDER) {

			table = alloc_pages_exact(size, gfp_flags);

			kmemleak_alloc(table, size, 1, gfp_flags);

		}

		}

	} while (!table && size > PAGE_SIZE && --log2qty);



	if (!table)

		panic("Failed to allocate %s hash table\n", tablename);



	pr_info("%s hash table entries: %ld (order: %d, %lu bytes)\n",

		tablename, 1UL << log2qty, ilog2(size) - PAGE_SHIFT, size);

	pr_info("%s hash table entries: %ld (order: %d, %lu bytes, %s)\n",

		tablename, 1UL << log2qty, ilog2(size) - PAGE_SHIFT, size,

		virt ? "vmalloc" : "linear");



	if (_hash_shift)

		*_hash_shift = log2qty;