From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2013520FA81 for ; Fri, 11 Apr 2025 11:42:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744371746; cv=none; b=Y0NkfWVeydBJibINRYTFIw5cR0PWb2DuLQjt9MxFmJZrLbUz6emarTuJJ+Bujmw6IjVUxB2KVXXpuOmrwc+k8BQ+sFpkO+kUcIvDhwjN0hFpMqatr37mYcjbntgMXpvuWOvx/Eev4+huuR54i6Ux7/HB/qX8D4hz3tJIdTpEneo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744371746; c=relaxed/simple; bh=I6aUlf76Hj9oWT5IUPqlEFEXUQbl+N0fO/0i+e7uNSw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FCXHUDW86jaDmlVRaJ/PFe2xkeKIJCcnJgGNC8+Mf2x9pIaMk7WNKgKiIO6bZvLGvPz/TrB9E4XOBZFAMmzIgxKQ5uASykN6MJ/Zx9yj/McASV94V8KViLA3/svqYQkVT4VIZKsSx8TsUv0/QbDXg0pP2lvy2kCN7Dd8Yr+mt34= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=APb9ELGb; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="APb9ELGb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744371743; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=PQvxCPteal/twSkIPQWB0ZTQdjoa0MyFaK2SpsJtBd4=; b=APb9ELGbZuKGx7mQ4q2qJzx5X8BA8dDjUZBReoNRGFGLTfYCwgOuUayrKeh0KDfIc/aW6y AUtupOlFjm+M/PJ6qlrCO/unA1D0EhLcbacY9GBeRrB/i4UPHt8xRXtmy+4AZDTfZ/cJ0E td4IER8U/m2Juvkps9zOdr3k2tJUW2g= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-344-PrPHMUzqPKihBeJxiBIG4g-1; Fri, 11 Apr 2025 07:42:20 -0400 X-MC-Unique: PrPHMUzqPKihBeJxiBIG4g-1 X-Mimecast-MFC-AGG-ID: PrPHMUzqPKihBeJxiBIG4g_1744371739 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7EDBD1800361; Fri, 11 Apr 2025 11:42:18 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.222]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 50B251808882; Fri, 11 Apr 2025 11:42:15 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 11 Apr 2025 13:41:42 +0200 (CEST) Date: Fri, 11 Apr 2025 13:41:38 +0200 From: Oleg Nesterov To: Christian Brauner Cc: linux-fsdevel@vger.kernel.org, Jeff Layton , Lennart Poettering , Daan De Meyer , Mike Yuan , linux-kernel@vger.kernel.org, Peter Ziljstra Subject: Re: [RFC PATCH] pidfs: ensure consistent ENOENT/ESRCH reporting Message-ID: <20250411114137.GD5322@redhat.com> References: <20250409-sesshaft-absurd-35d97607142c@brauner> <20250409-rohstoff-ungnade-d1afa571f32c@brauner> <20250409184040.GF32748@redhat.com> <20250410101801.GA15280@redhat.com> <20250410-barhocker-weinhandel-8ed2f619899b@brauner> <20250410131008.GB15280@redhat.com> <20250410-inklusive-kehren-e817ba060a34@brauner> <20250410-akademie-skaten-75bd4686ad6b@brauner> <20250411-tagwerk-server-313ff9395188@brauner> <20250411112532.GC5322@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250411112532.GC5322@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 On 04/11, Oleg Nesterov wrote: > > On 04/11, Christian Brauner wrote: > > > > > Looking close at this. Why is: > > > > > > if (type == PIDTYPE_PID) { > > > WARN_ON_ONCE(pid_has_task(pid, PIDTYPE_PID)); > > > wake_up_all(&pid->wait_pidfd); > > > } > > > > > > located in __change_pid()? The only valid call to __change_pid() with a NULL > > > argument and PIDTYPE_PID is from __unhash_process(), no? > > > > We used to perform free_pid() directly from __change_pid() so prior to > > v6.15 changes it wasn't possible. > > Yes, exactly ;) To clarify, it was actually possible because the caller, release_task(), does thread_pid = get_pid(p->thread_pid); before __exit_signal() and detach_pid(PIDTYPE_PID) uses the same task_struct->thread_pid. But I didn't want to rely on this fact. And it seems we can do another cleanup... We can kill the no longer needed get_pid/put_pid in release_task(). I'll send the patch. > > Now that we free the pids separately let's > > just move the notification into __unhash_process(). I have a patch ready > > for this. > > Agreed, > > Acked-by: Oleg Nesterov