Commit 8e2cdbcb authored Apr 29, 2013 by Johannes Weiner Committed by Linus Torvalds Apr 29, 2013

x86-64: fall back to regular page vmemmap on allocation failure



Memory hotplug can happen on a machine under load, memory shortness
and fragmentation, so huge page allocations for the vmemmap are not
guaranteed to succeed.

Try to fall back to regular pages before failing the hotplug event
completely.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Bernhard Schmidt <Bernhard.Schmidt@lrz.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent e8216da5

arch/x86/mm/init_64.c

+26 −20

Original line number	Diff line number	Diff line
		@@ -1303,12 +1303,11 @@ static int __meminit vmemmap_populate_hugepages(unsigned long start,

		pmd = pmd_offset(pud, addr);
		if (pmd_none(*pmd)) {
		pte_t entry;
		void *p;

		p = vmemmap_alloc_block_buf(PMD_SIZE, node);
		if (!p)
		return -ENOMEM;
		if (p) {
		pte_t entry;

		entry = pfn_pte(__pa(p) >> PAGE_SHIFT,
		PAGE_KERNEL_LARGE);
		@@ -1326,8 +1325,15 @@ static int __meminit vmemmap_populate_hugepages(unsigned long start,

		addr_end = addr + PMD_SIZE;
		p_end = p + PMD_SIZE;
		} else
		continue;
		}
		} else if (pmd_large(*pmd)) {
		vmemmap_verify((pte_t *)pmd, node, addr, next);
		continue;
		}
		pr_warn_once("vmemmap: falling back to regular page backing\n");
		if (vmemmap_populate_basepages(addr, next, node))
		return -ENOMEM;
		}
		return 0;
		}

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