The patch titled proc: make collect_sigign_sigcatch() rcu-safe has been removed from the -mm tree. Its filename was proc-make-collect_sigign_sigcatch-rcu-safe.patch This patch was dropped because it was withdrawn The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: proc: make collect_sigign_sigcatch() rcu-safe From: Oleg Nesterov <oleg@xxxxxxxxxx> Make collect_sigign_sigcatch() rcu-safe. The necessary changes are simple, use rcu_dereference() to get ->sighand and check it is not NULL. In theory, this ->sighand can be re-used under us (but it can't go away). We could check task->sighand == sighand once again after the main loop to prevent the race with exit/exec, but I don't think this is really needed for fs/proc. Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx> Cc: David Howells <dhowells@xxxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Roland McGrath <roland@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/array.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff -puN fs/proc/array.c~proc-make-collect_sigign_sigcatch-rcu-safe fs/proc/array.c --- a/fs/proc/array.c~proc-make-collect_sigign_sigcatch-rcu-safe +++ a/fs/proc/array.c @@ -234,13 +234,18 @@ static void render_sigset_t(struct seq_f seq_printf(m, "\n"); } +/* needs ->siglock or rcu_read_lock() */ static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign, sigset_t *catch) { + struct sighand_struct *sighand = rcu_dereference(p->sighand); struct k_sigaction *k; int i; - k = p->sighand->action; + if (unlikely(!sighand)) + return; + + k = sighand->action; for (i = 1; i <= _NSIG; ++i, ++k) { if (k->sa.sa_handler == SIG_IGN) sigaddset(ign, i); _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are linux-next.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 oom-select_bad_process-check-pf_kthread-instead-of-mm-to-skip-kthreads.patch oom-select_bad_process-pf_exiting-check-should-take-mm-into-account.patch oom-introduce-find_lock_task_mm-to-fix-mm-false-positives.patch oom-oom_forkbomb_penalty-move-thread_group_cputime-out-of-task_lock.patch oom-hold-tasklist_lock-when-dumping-tasks.patch oom-give-current-access-to-memory-reserves-if-it-has-been-killed.patch oom-avoid-sending-exiting-tasks-a-sigkill.patch oom-clean-up-oom_kill_task.patch oom-clean-up-oom_badness.patch oom-select_bad_process-never-choose-tasks-with-badness-==-0.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 exit-exit_notify-can-trust-signal-notify_count-0.patch exit-change-zap_other_threads-to-count-sub-threads.patch exit-avoid-sig-count-in-de_thread-__exit_signal-synchronization.patch exit-avoid-sig-count-in-__exit_signal-to-detect-the-group-dead-case.patch posix-cpu-timers-avoid-task-signal-=-null-checks.patch ia64-ptrace_attach_sync_user_rbs-avoid-task-signal-=-null-checks.patch fork-exit-move-tty_kref_put-outside-of-__cleanup_signal.patch signals-make-task_struct-signal-immutable-refcountable.patch signals-clear-signal-tty-when-the-last-thread-exits.patch signals-clear-signal-tty-when-the-last-thread-exits-fix.patch signals-kill-the-awful-task_rq_unlock_wait-hack.patch exit-__exit_signal-use-thread_group_leader-consistently.patch kill-the-obsolete-thread_group_cputime_free-and-taskstats_tgid_init-helpers.patch exit-move-taskstats_tgid_free-from-__exit_signal-to-free_signal_struct.patch check_unshare_flags-kill-the-bogus-clone_sighand-sig-count-check.patch proc-get_nr_threads-doesnt-need-siglock-any-longer.patch proc-make-collect_sigign_sigcatch-rcu-safe.patch proc_sched_show_task-use-get_nr_threads.patch keyctl_session_to_parent-use-thread_group_empty-to-check-singlethreadness.patch proc-turn-signal_struct-count-into-int-nr_threads.patch proc-turn-signal_struct-count-into-int-nr_threads-checkpatch-fixes.patch proc-cleanup-remove-unused-assignments.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html