coredump: construct the list of coredumping threads at startup time
binfmt->core_dump() has to iterate over the all threads in system in order to find the coredumping threads and construct the list using the GFP_ATOMIC allocations. With this patch each thread allocates the list node on exit_mm()'s stack and adds itself to the list. This allows us to do further changes: - simplify ->core_dump() - change exit_mm() to clear ->mm first, then wait for ->core_done. this makes the coredumping process visible to oom_kill - kill mm->core_done Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9d5b327bf1
Коммит
b564daf806
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@ -1604,6 +1604,8 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
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init_completion(&mm->core_done);
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init_completion(&core_state->startup);
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core_state->dumper.task = tsk;
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core_state->dumper.next = NULL;
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core_waiters = zap_threads(tsk, mm, core_state, exit_code);
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up_write(&mm->mmap_sem);
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@ -159,8 +159,14 @@ struct vm_area_struct {
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#endif
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};
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struct core_thread {
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struct task_struct *task;
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struct core_thread *next;
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};
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struct core_state {
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atomic_t nr_threads;
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struct core_thread dumper;
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struct completion startup;
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};
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@ -664,6 +664,7 @@ assign_new_owner:
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static void exit_mm(struct task_struct * tsk)
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{
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struct mm_struct *mm = tsk->mm;
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struct core_state *core_state;
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mm_release(tsk, mm);
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if (!mm)
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@ -676,11 +677,19 @@ static void exit_mm(struct task_struct * tsk)
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* group with ->mm != NULL.
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*/
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down_read(&mm->mmap_sem);
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if (mm->core_state) {
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core_state = mm->core_state;
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if (core_state) {
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struct core_thread self;
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up_read(&mm->mmap_sem);
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if (atomic_dec_and_test(&mm->core_state->nr_threads))
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complete(&mm->core_state->startup);
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self.task = tsk;
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self.next = xchg(&core_state->dumper.next, &self);
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/*
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* Implies mb(), the result of xchg() must be visible
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* to core_state->dumper.
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*/
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if (atomic_dec_and_test(&core_state->nr_threads))
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complete(&core_state->startup);
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wait_for_completion(&mm->core_done);
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down_read(&mm->mmap_sem);
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