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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=hoY+nVJd; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C43B9606A330; Mon, 26 Oct 2026 09:41:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=hoY+nVJd Received: by smtp.kernel.org (Postfix) with ESMTPSA id D56F11F031E2; Mon, 26 Oct 2026 09:41:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793007674; bh=fmErr11J4yiDe+oqOLxrAHXMe+lgqHj/gW1PNNiv0PY=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=hoY+nVJdTpF+bOnGRqA60bqEon5wES0uTDgRThXCOwAPT/eYwNotrJ8PurgaBDBH8 6RTUTlsQSoBeGbuLzwDPLxO6Tg9aX0DzEGmjJzZhajmJdWtdQFKWaGv+iqM+2uBKpu 026t64oG7a4GhVyDaiFRtUzs+QhNWsy1qp4OK/oABUnwArhQHMz6REf23JPiDPpyUt H3PBDpVbqxeuL8lP8i6Dj/GHiIrypsBVaNKkQxsf+1b7KTZ/1TIdboA/vnbPXaRbcE n8p/qSrc52pFTkI67KgPo+ShAyE6zmyE2/FC0JJN0+EVo+8neJxNDYKWgRVYf+Oiv/ WBm0YdS18Y/Ng== Message-ID: Date: Sun, 25 Oct 2026 13:43:55 +0100 X-Mailing-List: linux-efi@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: ppm: add PPM (Page-Plugger Under Memory) to Page Fault and Overcommit elimination To: dev12124 , linux-mm@kvack.org Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, ardb@kernel.org, keescook@chromium.org References: <20261024104552.394-1-joaoanandalima@gmail.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 10/24/26 12:45, dev12124 wrote: > Hi mm subsystem, Hi, > > This patch implements the Memory Tatic called PPM, Page-Plugger Under Memory. > The Main Objective is: Page Faults and Overcommit Elimination. > > A few points under additionate: > > 1. Allocation Handshake (ppm_kalloc): > Using the GFP_PLUG_MEMORY mask, the allocator completely bypasses > passive overcommit verification. It instantly isolates physical frames > on the RAM, maps the page table entries síncronamente, and forces the > Present Bit and Writable Bit to 1 before returning the address block > register to the CPU. > > 2. Desallocation Cleanup (ppm_kfree): > Triggered via the GFP_FREE_T parameter, the release phase executes an > immediate length truncation to 0. It forces a synchronous TLB > invalidation (via invlpg execution) and flushes the data out of the L3 > cache lines using clflushopt instructions before moving the hot clean > pages into a dedicated priority recycling pool. > > I additionate a Buffer/Cache with store important objects. Reading this description I have no idea what this patch does, what it tries to solve, and why anybody should spend their time to look into it. > --- > include/linux/ppm/gfp_types.h | 74 ++++++++++++++++ > include/linux/slab.h | 11 +++ > mm/memory.c | 158 ++++++++++++++++++++++++++++++++++ > 3 files changed, 243 insertions(+) > create mode 100644 include/linux/ppm/gfp_types.h > > diff --git a/include/linux/ppm/gfp_types.h b/include/linux/ppm/gfp_types.h > new file mode 100644 > index 000000000..741122b2d > --- /dev/null > +++ b/include/linux/ppm/gfp_types.h > @@ -0,0 +1,74 @@ > +/* > + Memory Tatic: PPM (Page-Plugger Under Memory). > + This File is for PPM Flags/Macros/Functions/Types. > + Engineer (brazilian): João Guilherme da Silva Freitas Lima > + */ > + > +/* Types Include Guards */ > +#ifndef __PPM_TYPES_MEMORY > +#define __PPM_TYPES_MEMORY > + > +typedef unsigned char uint8_t; > +typedef unsigned short uint16_t; > +typedef unsigned int uint32_t; > +typedef unsigned long long uint64_t; > +typedef uint64_t gfp_t; > +/* For errors in Allocation */ > +#define __PPM_ALLOC_ERROR -102 > +/* For errors in Desallocation */ > +#define __PPM_FREE_ERROR 0x04 > +/* For success */ > +#define __PPM_SUCCESS 0 > +#endif > + > +/* Functions Include Guards */ > +#ifndef __PPM_FUNCTIONS_MEMORY > +#define __PPM_FUNCTIONS_MEMORY > + > +/* Initializer */ > +void __init_ppm_memory(); > + > +/* Allocator Optimized */ > +int ppm_kalloc(unsigned long address, uint64_t size, gfp_t flags); > + > +/* Desallocator Optimized */ > +int ppm_kfree(uint64_t size); > + > +#endif > + > +/* Flags Include Guards */ > +#ifndef __PPM_FLAGS_MEMORY > +#define __PPM_FLAGS_MEMORY > + > +/* PPM inits/starts in Bit 54 of a > + 64-bit variable > + */ > +gfp_t GFP_PLUG_MEMORY = (1ULL << 54); > + > +/* For free memory, the Bit 55 is > + used > + */ > +gfp_t GFP_FREE_T = (1ULL << 55); > + > +#endif > + > +/* Macros Include Guards */ > +#ifndef __PPM_MACROS_MEMORY > +#define __PPM_MACROS_MEMORY > + > +/* For Kernel Kernel tests 2 Bits (54 and 55) in > + 1 Clock Cycle (or in small clocks, example: 5 Clocks), > + is used a mask using | > + */ > +gfp_t GFP_MASK = GFP_PLUG_MEMORY | GFP_FREE_T; > + > +#endif > + > +/* > + Notes: > + E-Mail of RFC: > + [RFC] mm: page-fault: overcommit: PPM (Page-Plugger Under Memory) > + > + > + Assigned-Off-by: João I don't know if I am supposed to laugh or cry ;) -- Cheers, David