The patch titled
coredump: shift down_write(mmap_sem) into coredump_wait()
has been added to the -mm tree. Its filename is
coredump-shift-down_writemmap_sem-into-coredump_wait.patch
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------------------------------------------------------
Subject: coredump: shift down_write(mmap_sem) into coredump_wait()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
- move the cprm.mm_flags checks up, before we take mmap_sem
- move down_write(mmap_sem) and ->core_state check from do_coredump()
to coredump_wait()
This simplifies the code and makes the locking symmetrical.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/exec.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)
diff -puN fs/exec.c~coredump-shift-down_writemmap_sem-into-coredump_wait fs/exec.c
--- a/fs/exec.c~coredump-shift-down_writemmap_sem-into-coredump_wait
+++ a/fs/exec.c
@@ -1659,12 +1659,15 @@ static int coredump_wait(int exit_code,
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
struct completion *vfork_done;
- int core_waiters;
+ int core_waiters = -EBUSY;
init_completion(&core_state->startup);
core_state->dumper.task = tsk;
core_state->dumper.next = NULL;
- core_waiters = zap_threads(tsk, mm, core_state, exit_code);
+
+ down_write(&mm->mmap_sem);
+ if (!mm->core_state)
+ core_waiters = zap_threads(tsk, mm, core_state, exit_code);
up_write(&mm->mmap_sem);
if (unlikely(core_waiters < 0))
@@ -1857,20 +1860,12 @@ void do_coredump(long signr, int exit_co
binfmt = mm->binfmt;
if (!binfmt || !binfmt->core_dump)
goto fail;
+ if (!__get_dumpable(cprm.mm_flags))
+ goto fail;
cred = prepare_creds();
if (!cred)
goto fail;
-
- down_write(&mm->mmap_sem);
- /*
- * If another thread got here first, or we are not dumpable, bail out.
- */
- if (mm->core_state || !__get_dumpable(cprm.mm_flags)) {
- up_write(&mm->mmap_sem);
- goto fail_creds;
- }
-
/*
* We cannot trust fsuid as being the "true" uid of the
* process nor do we know its entire history. We only know it
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
linux-next.patch
posix-cpu-timers-reset-expire-cache-when-no-timer-is-running.patch
cpu-timers-simplify-rlimit_cpu-handling.patch
cpu-timers-cleanup-arm_timer.patch
cpu-timers-return-correct-previous-timer-reload-value.patch
cpu-timers-change-sigev_none-timer-implementation.patch
cpu-timers-assure-to-not-iterate-over-all-threads-in-fastpath_timer_check.patch
cpu-timers-optimize-run_posix_cpu_timers.patch
proc-cleanup-remove-unused-assignments.patch
kmod-add-init-function-to-usermodehelper.patch
exec-replace-call_usermodehelper_pipe-with-use-of-umh-init-function-and-resolve-limit.patch
umh-creds-convert-call_usermodehelper_keys-to-use-subprocess_info-init.patch
umh-creds-kill-subprocess_info-cred-logic.patch
call_usermodehelper-no-need-to-unblock-signals.patch
wait_for_helper-sigchld-from-user-space-can-lead-to-use-after-free.patch
call_usermodehelper-simplify-fix-umh_no_wait-case.patch
call_usermodehelper-umh_wait_exec-ignores-kernel_thread-failure.patch
coredump-factor-out-the-not-ispipe-file-checks.patch
coredump-cleanup-ispipe-code.patch
coredump-factor-out-put_cred-calls.patch
coredump-shift-down_writemmap_sem-into-coredump_wait.patch
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