Subject: + mm-hugetlb-initialize-pg_reserved-for-tail-pages-of-gigantig-compound-pages-fix.patch added to -mm tree
To: akpm@xxxxxxxxxxxxxxxxxxxx,aarcange@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Thu, 10 Oct 2013 14:26:48 -0700
The patch titled
Subject: mm-hugetlb-initialize-pg_reserved-for-tail-pages-of-gigantig-compound-pages-fix
has been added to the -mm tree. Its filename is
mm-hugetlb-initialize-pg_reserved-for-tail-pages-of-gigantig-compound-pages-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-initialize-pg_reserved-for-tail-pages-of-gigantig-compound-pages-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-initialize-pg_reserved-for-tail-pages-of-gigantig-compound-pages-fix.patch
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------------------------------------------------------
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: mm-hugetlb-initialize-pg_reserved-for-tail-pages-of-gigantig-compound-pages-fix
tweak comment layout and grammar
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff -puN mm/hugetlb.c~mm-hugetlb-initialize-pg_reserved-for-tail-pages-of-gigantig-compound-pages-fix mm/hugetlb.c
--- a/mm/hugetlb.c~mm-hugetlb-initialize-pg_reserved-for-tail-pages-of-gigantig-compound-pages-fix
+++ a/mm/hugetlb.c
@@ -701,17 +701,15 @@ static void prep_compound_gigantic_page(
__SetPageTail(p);
/*
* For gigantic hugepages allocated through bootmem at
- * boot, it's safer to be consistent with the
- * not-gigantic hugepages and to clear the PG_reserved
- * bit from all tail pages too. Otherwse drivers using
- * get_user_pages() to access tail pages, may get the
- * reference counting wrong if they see the
- * PG_reserved bitflag set on a tail page (despite the
- * head page didn't have PG_reserved set). Enforcing
- * this consistency between head and tail pages,
- * allows drivers to optimize away a check on the head
- * page when they need know if put_page is needed after
- * get_user_pages() or not.
+ * boot, it's safer to be consistent with the not-gigantic
+ * hugepages and clear the PG_reserved bit from all tail pages
+ * too. Otherwse drivers using get_user_pages() to access tail
+ * pages may get the reference counting wrong if they see
+ * PG_reserved set on a tail page (despite the head page not
+ * having PG_reserved set). Enforcing this consistency between
+ * head and tail pages allows drivers to optimize away a check
+ * on the head page when they need know if put_page() is needed
+ * after get_user_pages().
*/
__ClearPageReserved(p);
set_page_count(p, 0);
_
Patches currently in -mm which might be from akpm@xxxxxxxxxxxxxxxxxxxx are
arch-alpha-kernel-systblss-remove-debug-check.patch
i-need-old-gcc.patch
ipc-update-locking-scheme-comments-fix.patch
mm-zswap-bugfix-memory-leak-when-invalidate-and-reclaim-occur-concurrently-checkpatch-fixes.patch
mm-hugetlb-initialize-pg_reserved-for-tail-pages-of-gigantig-compound-pages-fix.patch
kernel-time-tick-commonc-document-tick_do_timer_cpu.patch
makefile-enable-werror=implicit-int-and-werror=strict-prototypes-by-default.patch
mm-readaheadc-do_readhead-dont-check-for-readpage.patch
posix_acl-uninlining.patch
mm.patch
mm-thp-khugepaged-add-policy-for-finding-target-node-fix.patch
mm-hugetlb-convert-hugetlbfs-to-use-split-pmd-lock-checkpatch-fixes.patch
x86-mm-enable-split-page-table-lock-for-pmd-level-checkpatch-fixes.patch
kernel-printk-printkc-convert-to-pr_foo.patch
maintainers-remove-richard-purdie-as-backlight-maintainer-fix.patch
checkpatch-extend-camelcase-types-and-ignore-existing-camelcase-uses-in-a-patch.patch
checkpatch-add-test-for-defines-of-arch_has_foo.patch
epoll-do-not-take-global-epmutex-for-simple-topologies-fix.patch
binfmt_elfc-use-get_random_int-to-fix-entropy-depleting.patch
init-do_mounts_rdc-fix-null-pointer-dereference-while-loading-initramfs-fix.patch
fat-additions-to-support-fat_fallocate.patch
fat-additions-to-support-fat_fallocate-v6-checkpatch-fixes.patch
gcov-add-support-for-gcc-47-gcov-format-fix.patch
gcov-add-support-for-gcc-47-gcov-format-fix-fix.patch
gcov-add-support-for-gcc-47-gcov-format-checkpatch-fixes.patch
kernel-modulec-use-pr_foo.patch
kernel-gcov-fsc-use-pr_warn.patch
linux-next.patch
linux-next-git-rejects.patch
mm-drop-actor-argument-of-do_generic_file_read-fix.patch
debugging-keep-track-of-page-owners-fix-2-fix.patch
debugging-keep-track-of-page-owners-fix-2-fix-fix-fix.patch
journal_add_journal_head-debug.patch
kernel-forkc-export-kernel_thread-to-modules.patch
mutex-subsystem-synchro-test-module.patch
slab-leaks3-default-y.patch
put_bh-debug.patch
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