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Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1keulf-00086P-0i; Tue, 17 Nov 2020 06:47:07 +0000 Received: from mail-qv1-xf44.google.com ([2607:f8b0:4864:20::f44]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1keulb-00085v-HB for linux-nvme@lists.infradead.org; Tue, 17 Nov 2020 06:47:05 +0000 Received: by mail-qv1-xf44.google.com with SMTP id 63so10141101qva.7 for ; Mon, 16 Nov 2020 22:47:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=from:references:in-reply-to:mime-version:thread-index:date :message-id:subject:to:cc; bh=RRbH7EZSSZpR4lAXMkmEaKSkj9hItve4rulEIgIl1vo=; b=BGZPt0Hu4so7TCd/htYpNOOzkB2NZBsbXrZm99bSEB6pX1wxTAEd7pcc9/RubcR8wA j5w7U2sTzxrexFuDBjZPG5V3/pc7j7Zk7Np3uvdVwqWLZkTohlcJfo/ojRE1x3ff6EtT decNqqqnVahkbohmS4UKlIsHQaaFRX1d542bA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:references:in-reply-to:mime-version :thread-index:date:message-id:subject:to:cc; bh=RRbH7EZSSZpR4lAXMkmEaKSkj9hItve4rulEIgIl1vo=; b=IAcl/9mcdg1e+hJcdqvGheqgHxa18kLICuYs45zJAPAdsf9hmhtbJyFSCRvjeKRmzz FXZNUhjqDfu98WhFnM1u8lvL1/sY4kqaeFdpbE7dJ2AEoGp+RZvt9QauU+2AqZ//aMpf EYcY7kvyeb1/GyEaqd0HE5/YOQXB0vTqqg3MEXzsCsJyVRocyA8VyE2SlFYRpFA0rmve cptMpXfxrxvZuj0cEaXPGW0FeqTZnADxb8LxhqSGGm/ONcNxSPv5n7MupRxQX/hRaITL vDwNpTFhSSf8q0NRDldjmK2yohNP+xMbYBeGBVZxXQkWDJOp57zkpdy9XhnpyMWZFuKm XHzw== X-Gm-Message-State: AOAM530U03Fvh9MRZCtvDca+ObeT85WZiVidiVQ8wELklTEsdvDx0BVK riSe3vgPSlWVNbyOkXvzho/Xjo4j5ypOc5LgGcz6CA== X-Google-Smtp-Source: ABdhPJxR5X9YKoGH7anocalEoeslgOqOFs4IdOXJSA1oi2SyRuXDW7Vhk7w9WjUlsCwIDApAiiOG9rvf+xrcRnH/QC0= X-Received: by 2002:ad4:42a7:: with SMTP id e7mr18951039qvr.45.1605595620558; Mon, 16 Nov 2020 22:47:00 -0800 (PST) From: Kashyap Desai References: <20201112075526.947079-1-ming.lei@redhat.com> <20201112075526.947079-2-ming.lei@redhat.com> <20201116172658.GJ22007@lst.de> <20201117010448.GA56247@T590> <20201117011610.GB56247@T590> In-Reply-To: <20201117011610.GB56247@T590> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 15.0 Thread-Index: AQGhTJgEfGK8+PW9LSmG4d1uyQPiiAGPnylrAa3LhY0CHCFjcQJwP7uAqfhysrA= Date: Tue, 17 Nov 2020 12:16:56 +0530 Message-ID: <18faec7d7c554cef81d3ff4f39a331f3@mail.gmail.com> Subject: RE: [PATCH 1/3] blk-mq: add new API of blk_mq_hctx_set_fq_lock_class To: Ming Lei , Christoph Hellwig X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201117_014703_611837_05110F6E X-CRM114-Status: GOOD ( 18.49 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jens Axboe , Bart Van Assche , Qian Cai , John Garry , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, Sumit Saxena , Hannes Reinecke Content-Type: multipart/mixed; boundary="===============5487573125986773565==" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org --===============5487573125986773565== Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="000000000000a5675405b447dcbc" --000000000000a5675405b447dcbc Content-Type: text/plain; charset="UTF-8" > On Tue, Nov 17, 2020 at 09:05:04AM +0800, Ming Lei wrote: > > On Mon, Nov 16, 2020 at 06:26:58PM +0100, Christoph Hellwig wrote: > > > On Thu, Nov 12, 2020 at 03:55:24PM +0800, Ming Lei wrote: > > > > flush_end_io() may be called recursively from some driver, such as > > > > nvme-loop, so lockdep may complain 'possible recursive locking'. > > > > Commit b3c6a5997541("block: Fix a lockdep complaint triggered by > > > > request queue flushing") tried to address this issue by assigning > > > > dynamically allocated per-flush-queue lock class. This solution > > > > adds synchronize_rcu() for each hctx's release handler, and causes > > > > horrible SCSI MQ probe delay(more than half an hour on megaraid sas). > > > > > > > > Add new API of blk_mq_hctx_set_fq_lock_class() for these drivers, > > > > so we just need to use driver specific lock class for avoiding the > > > > lockdep warning of 'possible recursive locking'. > > > > > > I'd turn this into an inline function to avoid the (although very > > > minimal) cost when LOCKDEP is not enabled. > > > > blk_mq_hctx_set_fq_lock_class() is just one-shot thing, do you really > > care the cost? > > Forget to mention, 'blk_flush_queue' is one private structure inside block > layer, so we can't define as inline. Original issue reported by Qian is fixed by this patch series. Tested on MegaRaid h/w. Tested-by: Kashyap Desai > > thanks, > Ming --000000000000a5675405b447dcbc Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIIQRQYJKoZIhvcNAQcCoIIQNjCCEDICAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg gg2aMIIE6DCCA9CgAwIBAgIOSBtqCRO9gCTKXSLwFPMwDQYJKoZIhvcNAQELBQAwTDEgMB4GA1UE CxMXR2xvYmFsU2lnbiBSb290IENBIC0gUjMxEzARBgNVBAoTCkdsb2JhbFNpZ24xEzARBgNVBAMT Ckdsb2JhbFNpZ24wHhcNMTYwNjE1MDAwMDAwWhcNMjQwNjE1MDAwMDAwWjBdMQswCQYDVQQGEwJC RTEZMBcGA1UEChMQR2xvYmFsU2lnbiBudi1zYTEzMDEGA1UEAxMqR2xvYmFsU2lnbiBQZXJzb25h bFNpZ24gMiBDQSAtIFNIQTI1NiAtIEczMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA tpZok2X9LAHsYqMNVL+Ly6RDkaKar7GD8rVtb9nw6tzPFnvXGeOEA4X5xh9wjx9sScVpGR5wkTg1 fgJIXTlrGESmaqXIdPRd9YQ+Yx9xRIIIPu3Jp/bpbiZBKYDJSbr/2Xago7sb9nnfSyjTSnucUcIP ZVChn6hKneVGBI2DT9yyyD3PmCEJmEzA8Y96qT83JmVH2GaPSSbCw0C+Zj1s/zqtKUbwE5zh8uuZ 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--===============5487573125986773565== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme --===============5487573125986773565==--