Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 3.13.y-ckt 118/132] mm: fix potential infinite loop in dissolve_free_huge_pages() | Date | Wed, 22 Jul 2015 19:00:36 -0700 |
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3.13.11-ckt24 -stable review patch. If anyone has any objections, please let me know.
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From: Li Zhong <zhong@linux.vnet.ibm.com>
commit d0177639310d23c7739500df3c6ce6fdfe34acec upstream.
It is possible for some platforms, such as powerpc to set HPAGE_SHIFT to 0 to indicate huge pages not supported.
When this is the case, hugetlbfs could be disabled during boot time: hugetlbfs: disabling because there are no supported hugepage sizes
Then in dissolve_free_huge_pages(), order is kept maximum (64 for 64bits), and the for loop below won't end: for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order)
As suggested by Naoya, below fix checks hugepages_supported() before calling dissolve_free_huge_pages().
[rientjes@google.com: no legitimate reason to call dissolve_free_huge_pages() when !hugepages_supported()] Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [ kamal: 3.13-stable prereq for 641844f mm/hugetlb: introduce minimum hugepage order ] Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- mm/hugetlb.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 072b673..3b9d346 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -920,6 +920,9 @@ void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn) unsigned long pfn; struct hstate *h; + if (!hugepages_supported()) + return; + /* Set scan step to minimum hugepage size */ for_each_hstate(h) if (order > huge_page_order(h)) -- 1.9.1
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