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charset="utf-8" Content-Transfer-Encoding: base64 Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org SGkgUGV0ciwKCk9uIFR1ZSwgQXVnIDEzLCAyMDI0IGF0IDEwOjQwOjA2QU0gKzAyMDAsIFBldHIg VGVzYcWZw61rIHdyb3RlOgo+IE9uIFR1ZSwgNiBBdWcgMjAyNCAyMDozNDo0MiArMDEwMAo+IENh dGFsaW4gTWFyaW5hcyA8Y2F0YWxpbi5tYXJpbmFzQGFybS5jb20+IHdyb3RlOgo+ID4gSSBoYXZl bid0IHRyaWVkIGJ1dCBpdCdzIHBvc3NpYmxlIHRoYXQgdGhpcyBwYXRjaCBhbHNvIGJyZWFrcyB0 aG9zZQo+ID4gYXJtNjQgcGxhdGZvcm1zIHdpdGggYWxsIFJBTSBhYm92ZSA0R0Igd2hlbiBDUkFT SF9BRERSX0xPV19NQVggaXMKPiA+IG1lbWJsb2NrX2VuZF9vZl9EUkFNKCkuIEhlcmUgYWxsIG1l bW9yeSB3b3VsZCBiZSBsb3cgYW5kIGluIHRoZSBhYnNlbmNlCj4gPiBvZiBubyBmYWxsYmFjaywg aXQgZmFpbHMgdG8gYWxsb2NhdGUuCj4gCj4gSSdtIGFmcmFpZCB5b3UndmUganVzdCBvcGVuZWQg YSBQYW5kb3JhIGJveC4uLiA7LSkKCk5vdCB0aGF0IGJhZCA7KSBidXQsIHllYWgsIHRoaXMgcGF0 Y2ggd2FzIGRyb3BwZWQgaW4gZmF2b3VyIG9mIHRoaXM6CgpodHRwczovL2xvcmUua2VybmVsLm9y Zy9yLzIwMjQwODEyMDYyMDE3LjI2NzQ0NDEtMS1ydWFuamluamllQGh1YXdlaS5jb20vCgo+IEFu b3RoZXIgKHVucmVsYXRlZCkgcGF0Y2ggc2VyaWVzIG1hZGUgdXMgYXdhcmUgb2YgYSBwbGF0Zm9y bXMgd2hlcmUgUkFNCj4gc3RhcnRzIGF0IDMyRywgYnV0IElJVUMgdGhlIGhvc3QgYnJpZGdlIG1h cHMgMzJHLTMzRyB0byBidXMgYWRkcmVzc2VzCj4gMC0xRywgYW5kIHRoZXJlIGlzIGEgZGV2aWNl IG9uIHRoYXQgYnVzIHdoaWNoIGNhbiBwcm9kdWNlIG9ubHkgMzAtYml0Cj4gYWRkcmVzc2VzLgo+ IAo+IE5vdywgd2hhdCB3YXMgdGhlIGlkZWEgYmVoaW5kIGFsbG9jYXRpbmcgc29tZSBjcmFzaCBt ZW1vcnkgImxvdyI/Cj4gUmlnaHQsIGl0IHNob3VsZCBhbGxvdyB0aGUgY3Jhc2gga2VybmVsIHRv IGFjY2VzcyBkZXZpY2VzIHdpdGgKPiBhZGRyZXNzaW5nIGNvbnN0cmFpbnRzLiBTbywgb24gdGhl IGFib3ZlLW1lbnRpb25lZCBwbGF0Zm9ybSwgYWxsb2NhdGluZwo+ICJsb3ciIHdvdWxkIGluIGZh Y3QgbWVhbiBhbGxvY2F0aW5nIGJldHdlZW4gMzJHIGFuZCAzM0cgKGluIGhvc3QgYWRkcmVzcwo+ IGRvbWFpbikuCgpJbmRlZWQuIElmIHRoYXQncyBub3QgYXZhaWxhYmxlLCB0aGUgY3Jhc2gga2Vy bmVsIHdvbid0IGJlIGFibGUgdG8gYm9vdAoodW5sZXNzIHRoZSBjb3JyZXNwb25kaW5nIGRldmlj ZSBpcyByZW1vdmVkIGZyb20gRFQgb3IgQUNQSSB0YWJsZXMpLgoKPiBTaG91bGQgd2UgcmV0aGlu ayB0aGUgd2hvbGUgY29uY2VwdCBvZiBoaWdoL2xvdz8KClllYWgsIGl0IHdvdWxkIGJlIGdvb2Qg dG8gcmV2aXNpdCB0aG9zZSBhdCBzb21lIHBvaW50LiBGb3IgdGhlIHRpbWUKYmVpbmcsICdsb3cn IGluIHRoaXMgY29udGV4dCBvbiBhcm02NCBtZWFucyBaT05FX0RNQSBtZW1vcnksIGJhc2ljYWxs eQp0aGUgY29tbW9uIGRlbm9taW5hdG9yIGFkZHJlc3MgcmFuZ2UgdGhhdCBzdXBwb3J0cyBhbGwg ZGV2aWNlcyBvbiBhbgpTb0MuIEZvciBvdGhlcnMgbGlrZSB4ODZfMzIsIHRoaXMgbWVhbnMgdGhl IG1lbW9yeSB0aGF0IHRoZSBrZXJuZWwgY2FuCmFjdHVhbGx5IG1hcCAobm90IG5lY2Vzc2FyaWx5 IGRldmljZS9ETUEgcmVsYXRlZCkuCgpTbywgaXQncyBub3QgYWx3YXlzIGFib3V0IHRoZSBETUEg Y2FwYWJpbGl0aWVzIGJ1dCBhbHNvIHdoYXQgdGhlIGNyYXNoCmtlcm5lbCBjYW4gbWFwIChzbyBz b21ld2hhdCBkaWZmZXJlbnQgZnJvbSB0aGUgem9uZSBhbGxvY2F0b3IgY2FzZSB3ZSd2ZQpiZWVu IGRpc2N1c3NpbmcgaW4gb3RoZXIgdGhyZWFkcykuCgotLSAKQ2F0YWxpbgoKX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18Ka2V4ZWMgbWFpbGluZyBsaXN0Cmtl eGVjQGxpc3RzLmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3RzLmluZnJhZGVhZC5vcmcvbWFpbG1h bi9saXN0aW5mby9rZXhlYwo= 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 E6617C52D7C for ; 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Tue, 13 Aug 2024 12:05:19 +0000 Received: from sin.source.kernel.org ([145.40.73.55]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sdqGV-00000003bxf-1mCS; Tue, 13 Aug 2024 12:04:41 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 20BD3CE0FC9; Tue, 13 Aug 2024 12:04:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B67DCC4AF0B; Tue, 13 Aug 2024 12:04:33 +0000 (UTC) Date: Tue, 13 Aug 2024 13:04:31 +0100 From: Catalin Marinas To: Petr =?utf-8?B?VGVzYcWZw61r?= Cc: Baoquan He , Jinjie Ruan , vgoyal@redhat.com, dyoung@redhat.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, chenjiahao16@huawei.com, akpm@linux-foundation.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Will Deacon Subject: Re: [PATCH -next] crash: Fix riscv64 crash memory reserve dead loop Message-ID: References: <20240802090105.3871929-1-ruanjinjie@huawei.com> <20240813104006.520bf42d@mordecai.tesarici.cz> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240813104006.520bf42d@mordecai.tesarici.cz> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240813_050439_677537_C2108ACB X-CRM114-Status: GOOD ( 21.30 ) X-BeenThere: linux-riscv@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; 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Tue, 13 Aug 2024 12:05:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type: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; bh=hgU2zxbO4L9WwJ4Iy3G9S7gibS8Uxav3KIGUQEEyFZY=; b=YbjnhR5edBWbBrpg9sniziQZF9 xjH+mTnQ/mDQPnrct57TcrkweN2ykIt0qaELTfm1ZrXCTCjXe0ZUBLDXtP1B1Cu++axpX6kqN+y1K qGl1dfXMuCg4FdjWufFpdRFEh7nHUX6wtGUlFLxtcE408PwrwXkOzH2fCQQTccdDhVA4frvh6Nl1b lhDeOWN9KkASR1NO9j5dpTZ+6QAUv3UJV/tk/vyCvu70L7JRFln+54+bk9f2fCtz8ZtwlfxQK+vZH A8cU+Qo17jlSJYpBSEyBnilRxfczNW7nJyDdD3JMi394wYpJd6h0HbaAEQuFfxVaqJQb0MlbfkA+4 zoR9QkqA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sdqH8-00000003cAD-1eDl; Tue, 13 Aug 2024 12:05:18 +0000 Received: from sin.source.kernel.org ([145.40.73.55]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sdqGV-00000003bxf-1mCS; Tue, 13 Aug 2024 12:04:41 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 20BD3CE0FC9; Tue, 13 Aug 2024 12:04:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B67DCC4AF0B; Tue, 13 Aug 2024 12:04:33 +0000 (UTC) Date: Tue, 13 Aug 2024 13:04:31 +0100 From: Catalin Marinas To: Petr =?utf-8?B?VGVzYcWZw61r?= Cc: Baoquan He , Jinjie Ruan , vgoyal@redhat.com, dyoung@redhat.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, chenjiahao16@huawei.com, akpm@linux-foundation.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Will Deacon Subject: Re: [PATCH -next] crash: Fix riscv64 crash memory reserve dead loop Message-ID: References: <20240802090105.3871929-1-ruanjinjie@huawei.com> <20240813104006.520bf42d@mordecai.tesarici.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240813104006.520bf42d@mordecai.tesarici.cz> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240813_050439_677537_C2108ACB X-CRM114-Status: GOOD ( 21.30 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Petr, On Tue, Aug 13, 2024 at 10:40:06AM +0200, Petr Tesařík wrote: > On Tue, 6 Aug 2024 20:34:42 +0100 > Catalin Marinas wrote: > > I haven't tried but it's possible that this patch also breaks those > > arm64 platforms with all RAM above 4GB when CRASH_ADDR_LOW_MAX is > > memblock_end_of_DRAM(). Here all memory would be low and in the absence > > of no fallback, it fails to allocate. > > I'm afraid you've just opened a Pandora box... ;-) Not that bad ;) but, yeah, this patch was dropped in favour of this: https://lore.kernel.org/r/20240812062017.2674441-1-ruanjinjie@huawei.com/ > Another (unrelated) patch series made us aware of a platforms where RAM > starts at 32G, but IIUC the host bridge maps 32G-33G to bus addresses > 0-1G, and there is a device on that bus which can produce only 30-bit > addresses. > > Now, what was the idea behind allocating some crash memory "low"? > Right, it should allow the crash kernel to access devices with > addressing constraints. So, on the above-mentioned platform, allocating > "low" would in fact mean allocating between 32G and 33G (in host address > domain). Indeed. If that's not available, the crash kernel won't be able to boot (unless the corresponding device is removed from DT or ACPI tables). > Should we rethink the whole concept of high/low? Yeah, it would be good to revisit those at some point. For the time being, 'low' in this context on arm64 means ZONE_DMA memory, basically the common denominator address range that supports all devices on an SoC. For others like x86_32, this means the memory that the kernel can actually map (not necessarily device/DMA related). So, it's not always about the DMA capabilities but also what the crash kernel can map (so somewhat different from the zone allocator case we've been discussing in other threads). -- Catalin