Subject: + mm-thp-turn-compound_head-into-bug_onpagetail-in-get_huge_page_tail.patch added to -mm tree
To: oleg@xxxxxxxxxx,aarcange@xxxxxxxxxx,davej@xxxxxxxxxx,dvhart@xxxxxxxxxxxxxxx,mgorman@xxxxxxx,peterz@xxxxxxxxxxxxx,tglx@xxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 16 Dec 2013 14:43:11 -0800
The patch titled
Subject: mm: thp: turn compound_head() into BUG_ON(!PageTail) in get_huge_page_tail()
has been added to the -mm tree. Its filename is
mm-thp-turn-compound_head-into-bug_onpagetail-in-get_huge_page_tail.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-turn-compound_head-into-bug_onpagetail-in-get_huge_page_tail.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-turn-compound_head-into-bug_onpagetail-in-get_huge_page_tail.patch
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: mm: thp: turn compound_head() into BUG_ON(!PageTail) in get_huge_page_tail()
get_huge_page_tail()->compound_head() looks confusing. Every caller must
check PageTail(page), otherwise atomic_inc(&page->_mapcount) is simply
wrong if this page is compound-trans-head.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxx>
Cc: Darren Hart <dvhart@xxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff -puN include/linux/mm.h~mm-thp-turn-compound_head-into-bug_onpagetail-in-get_huge_page_tail include/linux/mm.h
--- a/include/linux/mm.h~mm-thp-turn-compound_head-into-bug_onpagetail-in-get_huge_page_tail
+++ a/include/linux/mm.h
@@ -445,13 +445,12 @@ static inline bool compound_tail_refcoun
static inline void get_huge_page_tail(struct page *page)
{
/*
- * __split_huge_page_refcount() cannot run
- * from under us.
- * In turn no need of compound_trans_head here.
+ * __split_huge_page_refcount() cannot run from under us.
*/
+ VM_BUG_ON(!PageTail(page));
VM_BUG_ON(page_mapcount(page) < 0);
VM_BUG_ON(atomic_read(&page->_count) != 0);
- if (compound_tail_refcounted(compound_head(page)))
+ if (compound_tail_refcounted(page->first_page))
atomic_inc(&page->_mapcount);
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
mm-thp-__get_page_tail_foll-can-use-get_huge_page_tail.patch
mm-thp-turn-compound_head-into-bug_onpagetail-in-get_huge_page_tail.patch
introduce-for_each_thread-to-replace-the-buggy-while_each_thread.patch
oom_kill-change-oom_killc-to-use-for_each_thread.patch
oom_kill-has_intersects_mems_allowed-needs-rcu_read_lock.patch
oom_kill-add-rcu_read_lock-into-find_lock_task_mm.patch
autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch
autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch
coredump-set_dumpable-fix-the-theoretical-race-with-itself.patch
coredump-kill-mmf_dumpable-and-mmf_dump_securely.patch
coredump-make-__get_dumpable-get_dumpable-inline-kill-fs-coredumph.patch
proc-cleanup-simplify-get_task_state-task_state_array.patch
proc-fix-the-potential-use-after-free-in-first_tid.patch
proc-change-first_tid-to-use-while_each_thread-rather-than-next_thread.patch
proc-dont-abuse-group_leader-in-proc_task_readdir-paths.patch
proc-fix-f_pos-overflows-in-first_tid.patch
kernel-forkc-remove-redundant-null-check-in-dup_mm.patch
exec-check_unsafe_exec-use-while_each_thread-rather-than-next_thread.patch
exec-check_unsafe_exec-kill-the-dead-eagain-and-clear_in_exec-logic.patch
exec-move-the-final-allow_write_access-fput-into-free_bprm.patch
exec-kill-task_struct-did_exec.patch
fs-proc-arrayc-change-do_task_stat-to-use-while_each_thread.patch
kernel-sysc-k_getrusage-can-use-while_each_thread.patch
kernel-signalc-change-do_signal_stop-do_sigaction-to-use-while_each_thread.patch
linux-next.patch
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