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charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 648BF1A0008 X-Stat-Signature: kgyk3ows3fhnsbzxnnosd7hny77bjmh7 X-Rspam-User: X-HE-Tag: 1789917321-352383 X-HE-Meta: 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 Al1jq847 0GXwx1X1i1dBfqRyj+090HFUQbZMKCWkwJLy4CH62R2MN1X3dytf5yjzbD+nH7eZwMIyV1viFMDv7HPr8dCQe9dJbqfTZ6piX64cSQ1xeJOpCxkEhBcpkR8zoSYzmkBmlbg5fSJwhHuW4ceQrjp+HdlQC6w5MIgbbGDee+JXkbm9CHf1Dpsqm2stH2eUbPn0AZ2P8GNf8i1FH7i6YXt+BRSaAkdTQH3opHQcfcZ4R4R6b9nRhPAIPVK1uxZO6/Boyc9ZSj/S0W+9i7L+ujbol7OS8bt5xz7UuGuYYqB4e4sOLxU83aJuvpNo7WxsaM2+bpwPfUGAMi9dYDaAkqlSjtR9Yy/qvZlZ1MoOS Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 09/18, Christian Brauner wrote: > > So I thought a bit about this yesterday and had some brief discussions > bout this as well. I think we should kill this whole bug class by > ensuring that PF_USER_WORKERs never participate in a coredump. Agreed, > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -3021,6 +3021,21 @@ bool get_signal(struct ksignal *ksig) > */ > current->flags |= PF_SIGNALED; > > + /* > + * PF_USER_WORKER threads will catch and exit on fatal signals > + * themselves. They have cleanup that must be performed, so we > + * cannot call do_exit() on their behalf. Note that ksig won't > + * be properly initialized, PF_USER_WORKER's shouldn't use it. > + * > + * They must not dump core either. The dumper waits for every > + * other thread in the group to exit, and a sibling's exit path > + * may in turn wait for this worker's own exit, which only runs > + * after get_signal() returns: io_sq_thread() ends up in > + * io_wq_exit_workers() and waits there for its io-wq workers. > + */ > + if (current->flags & PF_USER_WORKER) > + goto out; This probably makes sense anyway... but see below. Perhaps it makes sense to change ptrace(PTRACE_SETSIGMASK) to fail if child->flags & PF_USER_WORKER ? Currently get_signal() from PF_USER_WORKER can only return SIGKILL, I think we should keep this rule. I don't think your change can fix all problems. Suppose we have a main thread T and a PF_USER_WORKER sub-thread W. Some signal, say, SIGHUP has a handler. Debugger unblocks SIGHUP for W. Now, kill(SIGHUP, T) can choose W as a target, complete_signal() can choose any thread if wants_signal(t) is true. W will "drop" this signal, its signal handler won't be called. In the longer term it would be nice to rework this logic somehow to not rely on ->blocked... Oleg.