From d67e03e361619b20c51aaef3b7dd1497617c371d Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 1 Sep 2021 11:23:38 -0500 Subject: exit: Factor coredump_exit_mm out of exit_mm Separate the coredump logic from the ordinary exit_mm logic by moving the coredump logic out of exit_mm into it's own function coredump_exit_mm. Link: https://lkml.kernel.org/r/87a6k2x277.fsf@disp2133 Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman" --- kernel/exit.c | 76 ++++++++++++++++++++++++++++++++--------------------------- 1 file changed, 41 insertions(+), 35 deletions(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index 91a43e57a32e..cb1619d8fd64 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -339,6 +339,46 @@ kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) } } +static void coredump_exit_mm(struct mm_struct *mm) +{ + struct core_state *core_state; + + /* + * Serialize with any possible pending coredump. + * We must hold mmap_lock around checking core_state + * and clearing tsk->mm. The core-inducing thread + * will increment ->nr_threads for each thread in the + * group with ->mm != NULL. + */ + core_state = mm->core_state; + if (core_state) { + struct core_thread self; + + mmap_read_unlock(mm); + + self.task = current; + if (self.task->flags & PF_SIGNALED) + self.next = xchg(&core_state->dumper.next, &self); + else + self.task = NULL; + /* + * Implies mb(), the result of xchg() must be visible + * to core_state->dumper. + */ + if (atomic_dec_and_test(&core_state->nr_threads)) + complete(&core_state->startup); + + for (;;) { + set_current_state(TASK_UNINTERRUPTIBLE); + if (!self.task) /* see coredump_finish() */ + break; + freezable_schedule(); + } + __set_current_state(TASK_RUNNING); + mmap_read_lock(mm); + } +} + #ifdef CONFIG_MEMCG /* * A task is exiting. If it owned this mm, find a new owner for the mm. @@ -434,47 +474,13 @@ assign_new_owner: static void exit_mm(void) { struct mm_struct *mm = current->mm; - struct core_state *core_state; exit_mm_release(current, mm); if (!mm) return; sync_mm_rss(mm); - /* - * Serialize with any possible pending coredump. - * We must hold mmap_lock around checking core_state - * and clearing tsk->mm. The core-inducing thread - * will increment ->nr_threads for each thread in the - * group with ->mm != NULL. - */ mmap_read_lock(mm); - core_state = mm->core_state; - if (core_state) { - struct core_thread self; - - mmap_read_unlock(mm); - - self.task = current; - if (self.task->flags & PF_SIGNALED) - self.next = xchg(&core_state->dumper.next, &self); - else - self.task = NULL; - /* - * Implies mb(), the result of xchg() must be visible - * to core_state->dumper. - */ - if (atomic_dec_and_test(&core_state->nr_threads)) - complete(&core_state->startup); - - for (;;) { - set_current_state(TASK_UNINTERRUPTIBLE); - if (!self.task) /* see coredump_finish() */ - break; - freezable_schedule(); - } - __set_current_state(TASK_RUNNING); - mmap_read_lock(mm); - } + coredump_exit_mm(mm); mmgrab(mm); BUG_ON(mm != current->active_mm); /* more a memory barrier than a real lock */ -- cgit v1.2.3