From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=170.10.133.124 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793183337; b=hP0TsQnu2YnTCD0rqcl1T4IJ6q9IldTlSqhBQz/XI8Ja5VthGFPbUAlWHykHqmn/rc+n 4kXNAJ0nGMyS1CEwn1/W1VRaG5QtOi+le3tgXlH+ox/WOgXx1z0dH/9sWrngTq9Hvycs8 t2rT2NrvJ2C21CmBikWWd8LXYi+5i6s2tWgBoTZ+iyDHJLH+IL9NX488DaEOsNNJa4Ch2 FW/sR27/uDE4XAjgCrp5UzkTJ+OJtlGFUH2/U7f3EOQmeswOrBxIMrEKtk+6MLmenmHLk N7jF/MeEMMFFLDc6285Z24X4ohAIM+0meoq0tgK/rtSeC7S8iSisG2zn30hdE1ssfeA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793183337; h=DMARC-Filter:DKIM-Signature:Received:X-MC-Unique: X-Mimecast-MFC-AGG-ID:Received:Received:From:To:Cc:Subject:Date: Message-ID:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding:X-Scanned-By; bh=t2VG8ghbsZ2ehmH3QK6+4qnOak7PHYZ/7p13exiaPw4=; b=PLJHEtoNt5R1k01g9LDRT+Q4ujUxFkvDVBOBkXb67tYk7lRjfh0srcOhPmbhaHnabK64 yXbO3mywb/x7DE+oQfb25dsOg8OXkT2KOHzAcjpBzEGzc6UNYLa8csmjPquuNGxnbWW+Q HXO9FBQRJxC5iwaQ2U7sszJzr5eRUs7R5RwQepT9AoN3Oa7oULcebTCcSt7eKjydlf9pv 6vkhJo68XDVQxa143Sxd+8xtRSM0vebOpM4vZLpKc20xydMmCi0EUkOcuMKehzzBzdt/s +HE3VIlUK6WMDDtK3rX7OmWvWoDsqJ25rHP1UaOGsHnU1t6WUmG3Inv+lu4o1fX1iUQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=HJ3XPD05; arc=none smtp.remote-ip=170.10.133.124 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 13102606A31A for ; Wed, 28 Oct 2026 10:28:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 13102606A31A 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, unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=HJ3XPD05 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1793183336; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=t2VG8ghbsZ2ehmH3QK6+4qnOak7PHYZ/7p13exiaPw4=; b=HJ3XPD058r6QxcufI8gA1zmJwAkJmCdbHddu4LJubhTXDdJ2Cb9sh+BpXvz8o6yvikfwxI Pe+1RuaL26XP0EzgYhQHgUsqyeT/vRiZG+zQvwt8/D0HR3ABhfJEGSS7F/yGCnUOvQ8oA8 teLzJE/+jId43LOS/1XGrhnHd9wSnVA= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-614-0aQtWSHpOb2hD8VZTNTAEA-1; Wed, 28 Oct 2026 06:28:52 -0400 X-MC-Unique: 0aQtWSHpOb2hD8VZTNTAEA-1 X-Mimecast-MFC-AGG-ID: 0aQtWSHpOb2hD8VZTNTAEA_1793183331 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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6C7C81955E8F; Wed, 28 Oct 2026 10:28:50 +0000 (UTC) Received: from snishika-thinkpadp16vgen1.tokyo.csb (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CA2BD1800444; Wed, 28 Oct 2026 10:28:45 +0000 (UTC) From: Seiji Nishikawa To: Keith Busch Cc: Seiji Nishikawa , Hannes Reinecke , Jens Axboe , Christoph Hellwig , Sagi Grimberg , Chris Leech , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] nvme-tcp: fix io_work priority inversion when send_mutex is held Date: Wed, 28 Oct 2026 19:28:42 +0900 Message-ID: <20261028102842.2192925-1-snishika@redhat.com> In-Reply-To: <20261023122351.977034-1-snishika@redhat.com> References: <20261014064524.4015025-1-snishika@redhat.com> <526673b4-a090-47a4-9181-e30813a8cbe5@suse.de> <20261023122351.977034-1-snishika@redhat.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Hello Keith, A short follow-up on this patch. The problem is a regression in v6.16 and later, and this is the minimal fix for it. It applies cleanly on the current nvme-7.4 branch. On the customer system, the unpatched kernel hung every time. With this patch, there has been no hang since October 15. blktests nvme over tcp passes with it, with the same results as without it. Hannes suggested removing the direct send path instead. I agree with that as a follow-up, and I will send it as a separate RFC patch for the next merge window, as I wrote in my previous mail. I can only test it on VMs, so the performance side needs testing by someone with a real nvme-tcp setup. It is a bigger change and not something for stable. Could this fix go into nvme-7.4, so that it can reach stable and the distro kernels? Please let me know if anything is missing. Thanks, Seiji