From: Aneesh Kumar K.V Date: Mon, 13 Jan 2014 06:04:24 +0000 (+0530) Subject: powerpc/thp: Fix crash on mremap X-Git-Tag: v3.14-rc1~81^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b3084f4db3aeb991c507ca774337c7e7893ed04f;p=pandora-kernel.git powerpc/thp: Fix crash on mremap This patch fix the below crash NIP [c00000000004cee4] .__hash_page_thp+0x2a4/0x440 LR [c0000000000439ac] .hash_page+0x18c/0x5e0 ... Call Trace: [c000000736103c40] [00001ffffb000000] 0x1ffffb000000(unreliable) [437908.479693] [c000000736103d50] [c0000000000439ac] .hash_page+0x18c/0x5e0 [437908.479699] [c000000736103e30] [c00000000000924c] .do_hash_page+0x4c/0x58 On ppc64 we use the pgtable for storing the hpte slot information and store address to the pgtable at a constant offset (PTRS_PER_PMD) from pmd. On mremap, when we switch the pmd, we need to withdraw and deposit the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset from new pmd. We also want to move the withdraw and deposit before the set_pmd so that, when page fault find the pmd as trans huge we can be sure that pgtable can be located at the offset. Signed-off-by: Aneesh Kumar K.V Acked-by: Kirill A. Shutemov Signed-off-by: Benjamin Herrenschmidt --- Reading git-diff-tree failed