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authorLinus Torvalds <torvalds@linux-foundation.org>2012-06-20 14:41:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-06-20 14:41:57 -0700
commita2a2609c97c1e21996b9d87d10d2c9ff07277524 (patch)
treec9db50783d6727f95d2a6b4c019c2d66952969d9 /include/asm-generic
parenta4d7a122385e27bdd91101635c704327d7c0d87f (diff)
parent48c3b583bbddad2220ca4c22319ca5d1f78b2090 (diff)
downloadlinux-a2a2609c97c1e21996b9d87d10d2c9ff07277524.tar.bz2
Merge branch 'akpm' (Andrew's patch-bomb)
* emailed from Andrew Morton <akpm@linux-foundation.org>: (21 patches) mm/memblock: fix overlapping allocation when doubling reserved array c/r: prctl: Move PR_GET_TID_ADDRESS to a proper place pidns: find_new_reaper() can no longer switch to init_pid_ns.child_reaper pidns: guarantee that the pidns init will be the last pidns process reaped fault-inject: avoid call to random32() if fault injection is disabled Viresh has moved get_maintainer: Fix --help warning mm/memory.c: fix kernel-doc warnings mm: fix kernel-doc warnings mm: correctly synchronize rss-counters at exit/exec mm, thp: print useful information when mmap_sem is unlocked in zap_pmd_range h8300: use the declarations provided by <asm/sections.h> h8300: fix use of extinct _sbss and _ebss xtensa: use the declarations provided by <asm/sections.h> xtensa: use "test -e" instead of bashism "test -a" xtensa: replace xtensa-specific _f{data,text} by _s{data,text} memcg: fix use_hierarchy css_is_ancestor oops regression mm, oom: fix and cleanup oom score calculations nilfs2: ensure proper cache clearing for gc-inodes thp: avoid atomic64_read in pmd_read_atomic for 32bit PAE ...
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/pgtable.h10
1 files changed, 10 insertions, 0 deletions
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 6f2b45a9b6bc..ff4947b7a976 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -484,6 +484,16 @@ static inline int pmd_none_or_trans_huge_or_clear_bad(pmd_t *pmd)
/*
* The barrier will stabilize the pmdval in a register or on
* the stack so that it will stop changing under the code.
+ *
+ * When CONFIG_TRANSPARENT_HUGEPAGE=y on x86 32bit PAE,
+ * pmd_read_atomic is allowed to return a not atomic pmdval
+ * (for example pointing to an hugepage that has never been
+ * mapped in the pmd). The below checks will only care about
+ * the low part of the pmd with 32bit PAE x86 anyway, with the
+ * exception of pmd_none(). So the important thing is that if
+ * the low part of the pmd is found null, the high part will
+ * be also null or the pmd_none() check below would be
+ * confused.
*/
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
barrier();