The patch titled
elf_core_dump: don't take tasklist_lock
has been added to the -mm tree. Its filename is
elf_core_dump-dont-take-tasklist_lock.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: elf_core_dump: don't take tasklist_lock
From: Oleg Nesterov <oleg@xxxxxxxxxx>
do_each_thread() is rcu-safe, and all tasks which use this ->mm must sleep
in wait_for_completion(&mm->core_done) at this point, so we can use RCU
locks.
Also, remove unneeded INIT_LIST_HEAD(new) before list_add(new, head).
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/binfmt_elf.c | 7 +++----
1 files changed, 3 insertions(+), 4 deletions(-)
diff -puN fs/binfmt_elf.c~elf_core_dump-dont-take-tasklist_lock fs/binfmt_elf.c
--- a/fs/binfmt_elf.c~elf_core_dump-dont-take-tasklist_lock
+++ a/fs/binfmt_elf.c
@@ -1479,20 +1479,19 @@ static int elf_core_dump(long signr, str
if (signr) {
struct elf_thread_status *tmp;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
do_each_thread(g,p)
if (current->mm == p->mm && current != p) {
tmp = kzalloc(sizeof(*tmp), GFP_ATOMIC);
if (!tmp) {
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
goto cleanup;
}
- INIT_LIST_HEAD(&tmp->list);
tmp->thread = p;
list_add(&tmp->list, &thread_list);
}
while_each_thread(g,p);
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
list_for_each(t, &thread_list) {
struct elf_thread_status *tmp;
int sz;
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
sys_getppid-oopses-on-debug-kernel-v2.patch
pid-implement-transfer_pid-and-use-it-to-simplify-de_thread.patch
pid-remove-temporary-debug-code-in-attach_pid.patch
rtmutex-clean-up-and-remove-some-extra-spinlocks.patch
rtmutex-clean-up-and-remove-some-extra-spinlocks-more.patch
elf_core_dump-dont-take-tasklist_lock.patch
pidhash-temporary-debug-checks.patch
-
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