Date: Tue, 19 Feb 2019 12:04:00 +0100 From: Borislav Petkov <bp@...en8.de> To: Rick Edgecombe <rick.p.edgecombe@...el.com> Cc: Andy Lutomirski <luto@...nel.org>, Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org, x86@...nel.org, hpa@...or.com, Thomas Gleixner <tglx@...utronix.de>, Nadav Amit <nadav.amit@...il.com>, Dave Hansen <dave.hansen@...ux.intel.com>, Peter Zijlstra <peterz@...radead.org>, linux_dti@...oud.com, linux-integrity@...r.kernel.org, linux-security-module@...r.kernel.org, akpm@...ux-foundation.org, kernel-hardening@...ts.openwall.com, linux-mm@...ck.org, will.deacon@....com, ard.biesheuvel@...aro.org, kristen@...ux.intel.com, deneen.t.dock@...el.com, "Rafael J. Wysocki" <rjw@...ysocki.net>, Pavel Machek <pavel@....cz> Subject: Re: [PATCH v2 14/20] mm: Make hibernate handle unmapped pages On Mon, Jan 28, 2019 at 04:34:16PM -0800, Rick Edgecombe wrote: > For architectures with CONFIG_ARCH_HAS_SET_ALIAS, pages can be unmapped > briefly on the directmap, even when CONFIG_DEBUG_PAGEALLOC is not > configured. So this changes kernel_map_pages and kernel_page_present to be s/this changes/change/ >From Documentation/process/submitting-patches.rst: "Describe your changes in imperative mood, e.g. "make xyzzy do frotz" instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy to do frotz", as if you are giving orders to the codebase to change its behaviour." Also, please end function names with parentheses. > defined when CONFIG_ARCH_HAS_SET_ALIAS is defined as well. It also changes > places (page_alloc.c) where those functions are assumed to only be > implemented when CONFIG_DEBUG_PAGEALLOC is defined. The commit message doesn't need to say "what" you're doing - that should be obvious from the diff below. It should rather say "why" you're doing it. > So now when CONFIG_ARCH_HAS_SET_ALIAS=y, hibernate will handle not present > page when saving. Previously this was already done when pages > CONFIG_DEBUG_PAGEALLOC was configured. It does not appear to have a big > hibernating performance impact. Comment over safe_copy_page() needs updating I guess. > Before: > [ 4.670938] PM: Wrote 171996 kbytes in 0.21 seconds (819.02 MB/s) > > After: > [ 4.504714] PM: Wrote 178932 kbytes in 0.22 seconds (813.32 MB/s) IINM, that's like 1734 pages more. How am I to understand this number? Code has called set_alias_nv_noflush() on them and safe_copy_page() now maps them one by one to copy them to the hibernation image? Thx. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
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