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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 1l4yU6-000780-1Z; Thu, 28 Jan 2021 04:00:42 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l4yU2-00077g-B0 for linux-arm-kernel@lists.infradead.org; Thu, 28 Jan 2021 04:00:39 +0000 Received: from [192.168.0.104] (c-73-42-176-67.hsd1.wa.comcast.net [73.42.176.67]) by linux.microsoft.com (Postfix) with ESMTPSA id 68AA620B7192; Wed, 27 Jan 2021 20:00:35 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 68AA620B7192 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1611806436; bh=j2ytaqRDLSxdVnbORmC1VmYaP/7+dbpAQywJI7b00gU=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=XjFkrXhHnyR53rne7WHNJDhhws91IZ+fiKsrlIcQYw4OfuqWziuNTJejFWJTYWfsT ReANiquNaEdr2UmAt9OkF/LasShgVDZT0lsMWLATFdmIKswUBTiXWvyfHyzINMiQoG QWAg7xvg2QTc/vkCRwtttTKCyBKFBTiHrO28Yypo= Subject: Re: [PATCH v15 09/10] arm64: Call kmalloc() to allocate DTB buffer To: Thiago Jung Bauermann , Will Deacon References: <20210115173017.30617-1-nramas@linux.microsoft.com> <20210115173017.30617-10-nramas@linux.microsoft.com> <20210127165208.GA358@willie-the-truck> <20210127184319.GA676@willie-the-truck> <871re5soof.fsf@manicouagan.localdomain> From: Lakshmi Ramasubramanian Message-ID: <58d3ffbf-4d80-c893-34d6-366ebfac55bd@linux.microsoft.com> Date: Wed, 27 Jan 2021 20:00:34 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <871re5soof.fsf@manicouagan.localdomain> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210127_230038_668864_DC26EF27 X-CRM114-Status: GOOD ( 26.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, benh@kernel.crashing.org, bhsharma@redhat.com, tao.li@vivo.com, zohar@linux.ibm.com, paulus@samba.org, vincenzo.frascino@arm.com, frowand.list@gmail.com, sashal@kernel.org, mpe@ellerman.id.au, masahiroy@kernel.org, jmorris@namei.org, takahiro.akashi@linaro.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, serge@hallyn.com, devicetree@vger.kernel.org, pasha.tatashin@soleen.com, prsriva@linux.microsoft.com, hsinyi@chromium.org, allison@lohutok.net, christophe.leroy@c-s.fr, mbrugger@suse.com, balajib@linux.microsoft.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, james.morse@arm.com, dmitry.kasatkin@gmail.com, linux-integrity@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 1/27/21 7:52 PM, Thiago Jung Bauermann wrote: > > Will Deacon writes: > >> On Wed, Jan 27, 2021 at 09:59:38AM -0800, Lakshmi Ramasubramanian wrote: >>> On 1/27/21 8:52 AM, Will Deacon wrote: >>> >>> Hi Will, >>> >>>> On Fri, Jan 15, 2021 at 09:30:16AM -0800, Lakshmi Ramasubramanian wrote: >>>>> create_dtb() function allocates kernel virtual memory for >>>>> the device tree blob (DTB). This is not consistent with other >>>>> architectures, such as powerpc, which calls kmalloc() for allocating >>>>> memory for the DTB. >>>>> >>>>> Call kmalloc() to allocate memory for the DTB, and kfree() to free >>>>> the allocated memory. >>>>> >>>>> Co-developed-by: Prakhar Srivastava >>>>> Signed-off-by: Prakhar Srivastava >>>>> Signed-off-by: Lakshmi Ramasubramanian >>>>> --- >>>>> arch/arm64/kernel/machine_kexec_file.c | 12 +++++++----- >>>>> 1 file changed, 7 insertions(+), 5 deletions(-) >>>>> >>>>> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c >>>>> index 7de9c47dee7c..51c40143d6fa 100644 >>>>> --- a/arch/arm64/kernel/machine_kexec_file.c >>>>> +++ b/arch/arm64/kernel/machine_kexec_file.c >>>>> @@ -29,7 +29,7 @@ const struct kexec_file_ops * const kexec_file_loaders[] = { >>>>> int arch_kimage_file_post_load_cleanup(struct kimage *image) >>>>> { >>>>> - vfree(image->arch.dtb); >>>>> + kfree(image->arch.dtb); >>>>> image->arch.dtb = NULL; >>>>> vfree(image->arch.elf_headers); >>>>> @@ -59,19 +59,21 @@ static int create_dtb(struct kimage *image, >>>>> + cmdline_len + DTB_EXTRA_SPACE; >>>>> for (;;) { >>>>> - buf = vmalloc(buf_size); >>>>> + buf = kmalloc(buf_size, GFP_KERNEL); >>>> >>>> Is there a functional need for this patch? I build the 'dtbs' target just >>>> now and sdm845-db845c.dtb is approaching 100K, which feels quite large >>>> for kmalloc(). >>> >>> Changing the allocation from vmalloc() to kmalloc() would help us further >>> consolidate the DTB setup code for powerpc and arm64. >> >> Ok, but at the risk of allocation failure. Can powerpc use vmalloc() >> instead? > > I believe this patch stems from this suggestion by Rob Herring: > >> This could be taken a step further and do the allocation of the new >> FDT. The difference is arm64 uses vmalloc and powerpc uses kmalloc. The >> arm64 version also retries with a bigger allocation. That seems >> unnecessary. > > in https://lore.kernel.org/linux-integrity/20201211221006.1052453-3-robh@kernel.org/ > > The problem is that this patch implements only part of the suggestion, > which isn't useful in itself. So the patch series should either drop > this patch or consolidate the FDT allocation between the arches. > > I just tested on powernv and pseries platforms and powerpc can use > vmalloc for the FDT buffer. > Thanks for verifying on powerpc platform Thiago. I'll update the patch to do the following: => Use vmalloc for FDT buffer allocation on powerpc => Keep vmalloc for arm64, but remove the retry on allocation. => Also, there was a memory leak of FDT buffer in the error code path on arm64, which I'll fix as well. Did I miss anything? thanks, -lakshmi _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel