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Mon, 21 Sep 2026 10:26:18 -0400 X-MC-Unique: zIc0_6r3NoSA_cJqD0Vc_A-1 X-Mimecast-MFC-AGG-ID: zIc0_6r3NoSA_cJqD0Vc_A_1790000776 Received: from mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.95]) (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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 422C11953994; Mon, 21 Sep 2026 14:26:15 +0000 (UTC) Received: from fedora (headnet03.pony-001.prod.iad2.dc.redhat.com [10.2.32.114]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 5D11B41D; Mon, 21 Sep 2026 14:26:11 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 21 Sep 2026 16:26:14 +0200 (CEST) Date: Mon, 21 Sep 2026 16:26:09 +0200 From: Oleg Nesterov To: Christian Brauner Cc: Chris Mason , linux-fsdevel@vger.kernel.org, Jens Axboe , Alexander Viro , Jan Kara , NeilBrown , Ingo Molnar , Peter Zijlstra , linux-mm@kvack.org, io-uring@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v3 14/17] fork: don't create io threads once PF_POSTCOREDUMP is set Message-ID: References: <20260921-work-coredump-fixes-v3-0-8e4adb1619e6@kernel.org> <20260921-work-coredump-fixes-v3-14-8e4adb1619e6@kernel.org> MIME-Version: 1.0 In-Reply-To: <20260921-work-coredump-fixes-v3-14-8e4adb1619e6@kernel.org> X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 X-Mimecast-MFC-PROC-ID: VbzgdjeNRZilgKcvjoUc_L_EQHUcixr3LXbl_F86tlc_1790000776 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 46D3220011 X-Stat-Signature: xf66uryprka97itwgooairt6m4fpnf9u X-Rspam-User: X-HE-Tag: 1790000782-888370 X-HE-Meta: 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 eU8UjgYs BLm/3vcCfP/05E1Q1Uv+O1EMIuESJNt9WdGs7iMlGi5hHM2R9QPsCMwhOdJek5bxSS94ypfo59QniPzsxm1jUVjOCAa2sSK6NDSoLAFxXXO6wxx782MhAvWG07ANxPgF671B0wmKVydSoQueYo9OfV594Wpyv47sbV9GtgHyrsauW8Ng2xg1s6ai4d6qrLcECSZoH3Xw6Glps5CtROoiN128P6CRAQ9+wfLpLuOm6MlFt4UKH1yqUpVFJ5p/r40j0SD7V8hDkaoXwi+rAWe0l3ZgQpQ9xIHwHAMlmnJEFZIeIJYWN/wlsOzwc6DfaxVZBShrUlCRBqh3WVPSLvN2vmNGsyJx8ZNG8+B87Kmws2X9+iy+tIs0DV+wZxt1L1uAV02nmRGc5u+hm5A2z8efjGPogl29Z/nxUYD9MWaVZPnOWxm4= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 09/21, Christian Brauner wrote: > > Refuse to create an io thread when the creator has PF_POSTCOREDUMP. > That costs nothing. io_uring_files_cancel() raises IO_WQ_BIT_EXIT > before it runs any task work, so a worker created from there only ever > gets to exit again, and io_should_retry_thread() doesn't retry -EINTR. Thanks for this note in the changelog, > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -2706,8 +2706,8 @@ struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node) > .user_worker = 1, > }; > > - /* A creator past its fatal signal gets no thread. */ > - if (current->flags & PF_SIGNALED) > + /* A creator past its fatal signal or its coredump point gets no thread. */ > + if (current->flags & (PF_SIGNALED | PF_POSTCOREDUMP)) > return ERR_PTR(-EINTR); Acked-by: Oleg Nesterov