On 8/17/21 5:28 PM, Jens Axboe wrote: > > Another approach - don't allow TWA_SIGNAL task_work to get queued if > PF_SIGNALED has been set on the task. This is similar to how we reject > task_work_add() on process exit, and the callers must be able to handle > that already. > > Can you test this one on top of your 5.10-stable? > > > diff --git a/fs/coredump.c b/fs/coredump.c > index 07afb5ddb1c4..ca7c1ee44ada 100644 > --- a/fs/coredump.c > +++ b/fs/coredump.c > @@ -602,6 +602,14 @@ void do_coredump(const kernel_siginfo_t *siginfo) > .mm_flags = mm->flags, > }; > > + /* > + * task_work_add() will refuse to add work after PF_SIGNALED has > + * been set, ensure that we flush any pending TIF_NOTIFY_SIGNAL work > + * if any was queued before that. > + */ > + if (test_thread_flag(TIF_NOTIFY_SIGNAL)) > + tracehook_notify_signal(); > + > audit_core_dumps(siginfo->si_signo); > > binfmt = mm->binfmt; > diff --git a/kernel/task_work.c b/kernel/task_work.c > index 1698fbe6f0e1..1ab28904adc4 100644 > --- a/kernel/task_work.c > +++ b/kernel/task_work.c > @@ -41,6 +41,12 @@ int task_work_add(struct task_struct *task, struct callback_head *work, > head = READ_ONCE(task->task_works); > if (unlikely(head == &work_exited)) > return -ESRCH; > + /* > + * TIF_NOTIFY_SIGNAL notifications will interfere with > + * a core dump in progress, reject them. > + */ > + if ((task->flags & PF_SIGNALED) && notify == TWA_SIGNAL) > + return -ESRCH; > work->next = head; > } while (cmpxchg(&task->task_works, head, work) != head); > > Doesn't compile. 5.10 doesn't have TIF_NOTIFY_SIGNAL. Tony Battersby
