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Peter Anvin" , Alexander Potapenko , Andrew Morton , Andy Shevchenko , Ard Biesheuvel , Borislav Petkov , Darren Hart , Dave Hansen , David Rientjes , Dmitry Vyukov , Ingo Molnar , Marco Elver , Thomas Gleixner , kasan-dev@googlegroups.com, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v2 1/1] mm: Always release pages to the buddy allocator in memblock_free_late(). In-Reply-To: References: <010101857bbc3a41-173240b3-9064-42ef-93f3-482081126ec2-000000@us-west-2.amazonses.com> <20230105041650.1485-1-dev@aaront.org> <010001858025fc22-e619988e-c0a5-4545-bd93-783890b9ad14-000000@email.amazonses.com> User-Agent: Roundcube Webmail/1.4.13 Message-ID: <0101018584d0b5a3-ea0e4d67-b00f-4254-8e1c-767fcafbec31-000000@us-west-2.amazonses.com> X-Sender: dev@aaront.org Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Feedback-ID: 1.us-west-2.OwdjDcIoZWY+bZWuVZYzryiuW455iyNkDEZFeL97Dng=:AmazonSES X-SES-Outgoing: 2023.01.06-54.240.27.53 X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C03F24000B X-Stat-Signature: hmeoo9344d1wf6s7phfg6b9rnfab3cmi X-HE-Tag: 1672970550-435100 X-HE-Meta: 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 Y7RJI33c TJ5eAt4XhUE5A4iJimf2K3VP6LLJD2E35B/KeJUjHfBDteO9r121KX2lLrnBqUjfBuIKwvjFiig0tqrodcvZIHn82kg6j8ND+JaEw095m73QKJH2R83AZ2ny5KeLXbg6O8bQR8SH1oT3eNCeD5iHdcS6Wx3rgHzrhvifAU30B0QbNXr61l0YNx+UtSdrt1My674XT+5s7Z1XFAkJMp2oF5pycDKf/nji3vj0lMyK7wAI3JrA5RuLJiQ+cHbjAeZpR0i6cTdXWuip6wzZLCR/v2E8G41fxGYJ4+fYIsw4yX8G/145uvVcIYL7m9EEuojm1UAPrnniGqa7jkmQz1tqn3xvRGfwPfjF/NULbldUPTUQFs+ucta48Uocg6GZwhrVGL2u6i545sHT6bbw= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2023-01-05 02:48, Ingo Molnar wrote: > * Aaron Thompson wrote: > >> For example, on an Amazon EC2 t3.micro VM (1 GB) booting via EFI: >> >> v6.2-rc2: >> # grep -E 'Node|spanned|present|managed' /proc/zoneinfo >> Node 0, zone DMA >> spanned 4095 >> present 3999 >> managed 3840 >> Node 0, zone DMA32 >> spanned 246652 >> present 245868 >> managed 178867 >> >> v6.2-rc2 + patch: >> # grep -E 'Node|spanned|present|managed' /proc/zoneinfo >> Node 0, zone DMA >> spanned 4095 >> present 3999 >> managed 3840 >> Node 0, zone DMA32 >> spanned 246652 >> present 245868 >> managed 222816 # +43,949 pages > > [ Note the annotation I added to the output - might be useful in the > changelog too. ] > > So this patch adds around +17% of RAM to this 1 GB virtual system? That > looks rather significant ... > > Thanks, > > Ingo It is significant, but I wouldn't describe it as being added. I would say that the system is currently losing 17% of RAM due to a bug, and this patch fixes that bug. The actual numbers depend on the mappings given by the EFI, so they're largely out of our control. As an example, similar VMs that I run with the OVMF EFI lose about 3%. I couldn't say for sure which is the outlier, but my point is that the specific values are not really the focus, this is just an example that shows that the issue can be encountered in the wild with real impact. I know I'll be happy to get that memory back, whether it is 3% or 17% :) Thanks, -- Aaron