From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B7CAC43334 for ; Wed, 6 Jul 2022 15:48:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234371AbiGFPsz (ORCPT ); Wed, 6 Jul 2022 11:48:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43556 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234331AbiGFPsJ (ORCPT ); Wed, 6 Jul 2022 11:48:09 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51DB72A279 for ; Wed, 6 Jul 2022 08:41:06 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D4881B81D8B for ; Wed, 6 Jul 2022 15:41:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E284AC3411C; Wed, 6 Jul 2022 15:40:59 +0000 (UTC) Date: Wed, 6 Jul 2022 16:40:56 +0100 From: Catalin Marinas To: "guanghui.fgh" Cc: Mike Rapoport , Will Deacon , Ard Biesheuvel , baolin.wang@linux.alibaba.com, akpm@linux-foundation.org, david@redhat.com, jianyong.wu@arm.com, james.morse@arm.com, quic_qiancai@quicinc.com, christophe.leroy@csgroup.eu, jonathan@marek.ca, mark.rutland@arm.com, thunder.leizhen@huawei.com, anshuman.khandual@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, geert+renesas@glider.be, linux-mm@kvack.org, yaohongbo@linux.alibaba.com, alikernel-developer@linux.alibaba.com Subject: Re: [PATCH v4] arm64: mm: fix linear mem mapping access performance degradation Message-ID: References: <5d044fdd-a61a-d60f-d294-89e17de37712@linux.alibaba.com> <20220705121115.GB1012@willie-the-truck> <9974bea5-4db9-0104-c9c9-d9b49c390f1b@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9974bea5-4db9-0104-c9c9-d9b49c390f1b@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 06, 2022 at 11:18:22PM +0800, guanghui.fgh wrote: > 在 2022/7/6 21:54, Mike Rapoport 写道: > > One thing I can think of is to only remap the crash kernel memory if it is > > a part of an allocation that exactly fits into one ore more PUDs. > > > > Say, in reserve_crashkernel() we try the memblock_phys_alloc() with > > PUD_SIZE as alignment and size rounded up to PUD_SIZE. If this allocation > > succeeds, we remap the entire area that now contains only memory allocated > > in reserve_crashkernel() and free the extra memory after remapping is done. > > If the large allocation fails, we fall back to the original size and > > alignment and don't allow unmapping crash kernel memory in > > arch_kexec_protect_crashkres(). > > There is a new method. > I think we should use the patch v3(similar but need add some changes) > > 1.We can walk crashkernle block/section pagetable, > [[[(keep the origin block/section mapping valid]]] > rebuild the pte level page mapping for the crashkernel mem > rebuild left & right margin mem(which is in same block/section mapping but > out of crashkernel mem) with block/section mapping > > 2.'replace' the origin block/section mapping by new builded mapping > iterately > > With this method, all the mem mapping keep valid all the time. As I already commented on one of your previous patches, this is not allowed by the architecture. If FEAT_BBM is implemented (ARMv8.4 I think), the worst that can happen is a TLB conflict abort and the handler should invalidate the TLBs and restart the faulting instruction, assuming the handler won't try to access the same conflicting virtual address. Prior to FEAT_BBM, that's not possible as the architecture does not describe a precise behaviour of conflicting TLB entries (you might as well get the TLB output of multiple entries being or'ed together). -- Catalin From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 614ABC43334 for ; Wed, 6 Jul 2022 15:42:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; 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Wed, 6 Jul 2022 15:41:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E284AC3411C; Wed, 6 Jul 2022 15:40:59 +0000 (UTC) Date: Wed, 6 Jul 2022 16:40:56 +0100 From: Catalin Marinas To: "guanghui.fgh" Cc: Mike Rapoport , Will Deacon , Ard Biesheuvel , baolin.wang@linux.alibaba.com, akpm@linux-foundation.org, david@redhat.com, jianyong.wu@arm.com, james.morse@arm.com, quic_qiancai@quicinc.com, christophe.leroy@csgroup.eu, jonathan@marek.ca, mark.rutland@arm.com, thunder.leizhen@huawei.com, anshuman.khandual@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, geert+renesas@glider.be, linux-mm@kvack.org, yaohongbo@linux.alibaba.com, alikernel-developer@linux.alibaba.com Subject: Re: [PATCH v4] arm64: mm: fix linear mem mapping access performance degradation Message-ID: References: <5d044fdd-a61a-d60f-d294-89e17de37712@linux.alibaba.com> <20220705121115.GB1012@willie-the-truck> <9974bea5-4db9-0104-c9c9-d9b49c390f1b@linux.alibaba.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <9974bea5-4db9-0104-c9c9-d9b49c390f1b@linux.alibaba.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220706_084107_260072_85091040 X-CRM114-Status: GOOD ( 22.47 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gV2VkLCBKdWwgMDYsIDIwMjIgYXQgMTE6MTg6MjJQTSArMDgwMCwgZ3VhbmdodWkuZmdoIHdy b3RlOgo+IOWcqCAyMDIyLzcvNiAyMTo1NCwgTWlrZSBSYXBvcG9ydCDlhpnpgZM6Cj4gPiBPbmUg dGhpbmcgSSBjYW4gdGhpbmsgb2YgaXMgdG8gb25seSByZW1hcCB0aGUgY3Jhc2gga2VybmVsIG1l bW9yeSBpZiBpdCBpcwo+ID4gYSBwYXJ0IG9mIGFuIGFsbG9jYXRpb24gdGhhdCBleGFjdGx5IGZp dHMgaW50byBvbmUgb3JlIG1vcmUgUFVEcy4KPiA+IAo+ID4gU2F5LCBpbiByZXNlcnZlX2NyYXNo a2VybmVsKCkgd2UgdHJ5IHRoZSBtZW1ibG9ja19waHlzX2FsbG9jKCkgd2l0aAo+ID4gUFVEX1NJ WkUgYXMgYWxpZ25tZW50IGFuZCBzaXplIHJvdW5kZWQgdXAgdG8gUFVEX1NJWkUuIElmIHRoaXMg YWxsb2NhdGlvbgo+ID4gc3VjY2VlZHMsIHdlIHJlbWFwIHRoZSBlbnRpcmUgYXJlYSB0aGF0IG5v dyBjb250YWlucyBvbmx5IG1lbW9yeSBhbGxvY2F0ZWQKPiA+IGluIHJlc2VydmVfY3Jhc2hrZXJu ZWwoKSBhbmQgZnJlZSB0aGUgZXh0cmEgbWVtb3J5IGFmdGVyIHJlbWFwcGluZyBpcyBkb25lLgo+ ID4gSWYgdGhlIGxhcmdlIGFsbG9jYXRpb24gZmFpbHMsIHdlIGZhbGwgYmFjayB0byB0aGUgb3Jp Z2luYWwgc2l6ZSBhbmQKPiA+IGFsaWdubWVudCBhbmQgZG9uJ3QgYWxsb3cgdW5tYXBwaW5nIGNy YXNoIGtlcm5lbCBtZW1vcnkgaW4KPiA+IGFyY2hfa2V4ZWNfcHJvdGVjdF9jcmFzaGtyZXMoKS4K PiAKPiBUaGVyZSBpcyBhIG5ldyBtZXRob2QuCj4gSSB0aGluayB3ZSBzaG91bGQgdXNlIHRoZSBw YXRjaCB2MyhzaW1pbGFyIGJ1dCBuZWVkIGFkZCBzb21lIGNoYW5nZXMpCj4gCj4gMS5XZSBjYW4g d2FsayBjcmFzaGtlcm5sZSBibG9jay9zZWN0aW9uIHBhZ2V0YWJsZSwKPiBbW1soa2VlcCB0aGUg b3JpZ2luIGJsb2NrL3NlY3Rpb24gbWFwcGluZyB2YWxpZF1dXQo+IHJlYnVpbGQgdGhlIHB0ZSBs ZXZlbCBwYWdlIG1hcHBpbmcgZm9yIHRoZSBjcmFzaGtlcm5lbCBtZW0KPiByZWJ1aWxkIGxlZnQg JiByaWdodCBtYXJnaW4gbWVtKHdoaWNoIGlzIGluIHNhbWUgYmxvY2svc2VjdGlvbiBtYXBwaW5n IGJ1dAo+IG91dCBvZiBjcmFzaGtlcm5lbCBtZW0pIHdpdGggYmxvY2svc2VjdGlvbiBtYXBwaW5n Cj4gCj4gMi4ncmVwbGFjZScgdGhlIG9yaWdpbiBibG9jay9zZWN0aW9uIG1hcHBpbmcgYnkgbmV3 IGJ1aWxkZWQgbWFwcGluZwo+IGl0ZXJhdGVseQo+IAo+IFdpdGggdGhpcyBtZXRob2QsIGFsbCB0 aGUgbWVtIG1hcHBpbmcga2VlcCB2YWxpZCBhbGwgdGhlIHRpbWUuCgpBcyBJIGFscmVhZHkgY29t bWVudGVkIG9uIG9uZSBvZiB5b3VyIHByZXZpb3VzIHBhdGNoZXMsIHRoaXMgaXMgbm90CmFsbG93 ZWQgYnkgdGhlIGFyY2hpdGVjdHVyZS4gSWYgRkVBVF9CQk0gaXMgaW1wbGVtZW50ZWQgKEFSTXY4 LjQgSQp0aGluayksIHRoZSB3b3JzdCB0aGF0IGNhbiBoYXBwZW4gaXMgYSBUTEIgY29uZmxpY3Qg YWJvcnQgYW5kIHRoZQpoYW5kbGVyIHNob3VsZCBpbnZhbGlkYXRlIHRoZSBUTEJzIGFuZCByZXN0 YXJ0IHRoZSBmYXVsdGluZyBpbnN0cnVjdGlvbiwKYXNzdW1pbmcgdGhlIGhhbmRsZXIgd29uJ3Qg dHJ5IHRvIGFjY2VzcyB0aGUgc2FtZSBjb25mbGljdGluZyB2aXJ0dWFsCmFkZHJlc3MuIFByaW9y IHRvIEZFQVRfQkJNLCB0aGF0J3Mgbm90IHBvc3NpYmxlIGFzIHRoZSBhcmNoaXRlY3R1cmUgZG9l cwpub3QgZGVzY3JpYmUgYSBwcmVjaXNlIGJlaGF2aW91ciBvZiBjb25mbGljdGluZyBUTEIgZW50 cmllcyAoeW91IG1pZ2h0CmFzIHdlbGwgZ2V0IHRoZSBUTEIgb3V0cHV0IG9mIG11bHRpcGxlIGVu dHJpZXMgYmVpbmcgb3InZWQgdG9nZXRoZXIpLgoKLS0gCkNhdGFsaW4KCl9fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmxpbnV4LWFybS1rZXJuZWwgbWFpbGlu ZyBsaXN0CmxpbnV4LWFybS1rZXJuZWxAbGlzdHMuaW5mcmFkZWFkLm9yZwpodHRwOi8vbGlzdHMu aW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2xpbnV4LWFybS1rZXJuZWwK