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Thu, 15 Oct 2020 00:54:17 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id A0368C433F1; Thu, 15 Oct 2020 00:54:17 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: sudaraja) by smtp.codeaurora.org (Postfix) with ESMTPSA id D433FC433C9; Thu, 15 Oct 2020 00:54:16 +0000 (UTC) MIME-Version: 1.0 Date: Wed, 14 Oct 2020 17:54:16 -0700 From: Sudarshan Rajagopalan To: Anshuman Khandual Subject: Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory In-Reply-To: References: <339118202d0a4741ec22f215830dc8d9ba1ccd49.1602542734.git.sudaraja@codeaurora.org> Message-ID: X-Sender: sudaraja@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201014_205419_321888_8B2CE7D4 X-CRM114-Status: GOOD ( 23.28 ) 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 , Gavin Shan , David Hildenbrand , Catalin Marinas , linux-kernel@vger.kernel.org, Steven Price , Logan Gunthorpe , Andrew Morton , Will Deacon , linux-arm-kernel@lists.infradead.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 2020-10-13 04:38, Anshuman Khandual wrote: > On 10/13/2020 04:35 AM, Sudarshan Rajagopalan wrote: >> When section mappings are enabled, we allocate vmemmap pages from >> physically >> continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). >> Section >> mappings are good to reduce TLB pressure. But when system is highly >> fragmented >> and memory blocks are being hot-added at runtime, its possible that >> such >> physically continuous memory allocations can fail. Rather than failing >> the >> memory hot-add procedure, add a fallback option to allocate vmemmap >> pages from >> discontinuous pages using vmemmap_populate_basepages(). > > There is a checkpatch warning here, which could be fixed while merging > ? > > WARNING: Possible unwrapped commit description (prefer a maximum 75 > chars per line) > #7: > When section mappings are enabled, we allocate vmemmap pages from > physically > > total: 0 errors, 1 warnings, 13 lines checked > Thanks Anshuman for the review. I sent out an updated patch fixing the checkpatch warning. >> >> Signed-off-by: Sudarshan Rajagopalan >> Reviewed-by: Gavin Shan >> Cc: Catalin Marinas >> Cc: Will Deacon >> Cc: Anshuman Khandual >> Cc: Mark Rutland >> Cc: Logan Gunthorpe >> Cc: David Hildenbrand >> Cc: Andrew Morton >> Cc: Steven Price > > Nonetheless, this looks fine. Did not see any particular problem > while creating an experimental vmemmap with interleaving section > and base page mapping. > > Reviewed-by: Anshuman Khandual > >> --- >> arch/arm64/mm/mmu.c | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 75df62fea1b6..44486fd0e883 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long >> start, unsigned long end, int node, >> void *p = NULL; >> >> p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap); >> - if (!p) >> - return -ENOMEM; >> + if (!p) { >> + if (vmemmap_populate_basepages(addr, next, node, altmap)) >> + return -ENOMEM; >> + continue; >> + } >> >> pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL)); >> } else >> Sudarshan -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel