From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout1.w1.samsung.com (mailout1.w1.samsung.com [210.118.77.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 10756438024 for ; Thu, 6 Aug 2026 10:11:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=210.118.77.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786011118; cv=none; b=bh9JFumQmQNVi4oD1q5Q6yoOuiFARLQZLvUoLu6dsOYjePRgXubVl4MwX/YJQqNKe+kYP3pRINcZjo/Wvx5lovJ4LvZaFQUS3RifYdb032et2hDa7aOD/6V5e7WEvYIFiiCNaOSSsXBcW67521hUx3dvCO2S+iPEFtDaujey4ko= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786011118; c=relaxed/simple; bh=GrMks8wwD581o3AfzSr5fNGlq3w7/eLjXayhOzSr/3M=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:From:In-Reply-To: Content-Type:References; b=oBIWL9V9qgyhKy5iKA1nodFB/tiH1Pq3XQ8debNa0c0IXzUOw75wDh1sxg9h2cbNXU326QiKtVhKyCVrMMJZl7GY/JXbG+5jlioSA9AAg/d7Vf4zkyV9CN7Ac/5uHhxfvKXj107Nm3Xup6JpHd2VAvC6Cqgd1dH+x92tzdVV8gs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b=hvQmoFjh; arc=none smtp.client-ip=210.118.77.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="hvQmoFjh" Received: from eucas1p1.samsung.com (unknown [182.198.249.206]) by mailout1.w1.samsung.com (KnoxPortal) with ESMTP id 20260806101153euoutp01653ba1b142a1688dc0e74bc91214c13c~JL6USE7GJ1716017160euoutp01v for ; Thu, 6 Aug 2026 10:11:53 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout1.w1.samsung.com 20260806101153euoutp01653ba1b142a1688dc0e74bc91214c13c~JL6USE7GJ1716017160euoutp01v DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1786011113; bh=IMZ8qkfhOLZiwmIb3BHX25zuCyq2Sc5EP83poQE1J/s=; h=Date:Subject:To:Cc:From:In-Reply-To:References:From; b=hvQmoFjhsU8p1u0MmlmWQL29zelrY+Be3zf5/NM0om2nSLLwwR8OCwjwyRhkzh+89 I3vMFQhnKJhD6HIP4oad6vEoWfBmu1Nz/d9n4e3A7pkAPAn110O65kmbZUBmOTYOw2 iQHtEA2bshV4VP0X4zV7Rhe85gM+nMNaHDF2ggf4= Received: from eusmtip1.samsung.com (unknown [203.254.199.221]) by eucas1p2.samsung.com (KnoxPortal) with ESMTPA id 20260806101152eucas1p213e701b4891db43e93acd1f9d3447abe~JL6T8R35N1126211262eucas1p2s; Thu, 6 Aug 2026 10:11:52 +0000 (GMT) Received: from [106.120.50.46] (unknown [106.120.50.46]) by eusmtip1.samsung.com (KnoxPortal) with ESMTPA id 20260806101151eusmtip1bacb3c8e11470851538ac16bd48c8b84~JL6Sik-9k2357923579eusmtip1r; Thu, 6 Aug 2026 10:11:51 +0000 (GMT) Message-ID: Date: Thu, 6 Aug 2026 12:11:50 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Betterbird (Windows) Subject: Re: [PATCH v5 0/8] kdump: reduce vmcore size and capture time To: Wandun Chen , catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, robh@kernel.org, saravanak@kernel.org, rppt@kernel.org, baoquan.he@linux.dev, pasha.tatashin@soleen.com, pratyush@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-mm@kvack.org, kexec@lists.infradead.org, iommu@lists.linux.dev Cc: kernel@xen0n.name, alex@ghiti.fr, akpm@linux-foundation.org, ruirui.yang@linux.dev, robin.murphy@arm.com Content-Language: en-US From: Marek Szyprowski In-Reply-To: <20260806093519.2907771-1-chenwandun1@gmail.com> Content-Transfer-Encoding: 7bit X-CMS-MailID: 20260806101152eucas1p213e701b4891db43e93acd1f9d3447abe X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20260806093541eucas1p169d6fcb31de09012bdfca326867e86d6 X-EPHeader: CA X-CMS-RootMailID: 20260806093541eucas1p169d6fcb31de09012bdfca326867e86d6 References: <20260806093519.2907771-1-chenwandun1@gmail.com> On 06.08.2026 11:35, Wandun Chen wrote: > From: Wandun Chen > > On SoCs that carve out large firmware-owned reserved memory (GPU, > camera ISP, ...), kdump currently dumps those carveouts as part of > system RAM even though their contents are firmware state that is not > useful for kernel crash analysis. > > This series introduces a 'dumpable' flag on struct reserved_mem and a > MEMBLOCK_NODUMP flag in memblock to filter vmcore ELF header on DT-based > architectures (arm64, riscv, loongarch). Reserved regions default to > non-dumpable and are marked MEMBLOCK_NODUMP so kdump omits them; > reusable CMA regions are explicitly marked dumpable in rmem_cma_setup() > because their pages are handed back to the buddy allocator and may carry > crash-relevant data. > > Since the reserved memory regions are filtered out, the vmcore is > smaller in size and faster to produce. ACPI systems already filter > reserved memory out of the vmcore through their existing path; only > DT-based systems currently fail to filter these regions, which is what > this series addresses. The flag lives in memblock itself rather than > in a DT-only structure, so the mechanism is generic and both ACPI and > DT systems can benefit from it (suggested by Rob, thanks). > > The series is based on linux-next and is organized as follows: > Patches 1-2: Introduce MEMBLOCK_NODUMP in memblock and the dumpable > flag on struct reserved_mem. > Patches 3-4: Mark non-dumpable /reserved-memory and /memreserve/ > entries with MEMBLOCK_NODUMP. > Patch 5: Switch riscv to memblock so the NODUMP flag is visible > to the vmcore ELF header builder; add (KEXEC_FILE && > CRASH_DUMP) to riscv's ARCH_KEEP_MEMBLOCK condition. > Patches 6-8: Fold the duplicated per-arch memblock walks into the > weak defaults in crash_core, switch to > for_each_mem_region(), and exclude MEMBLOCK_NODUMP > regions from the vmcore ELF header. > > v4 --> v5: > 1. Rework the mechanism around a memblock-level MEMBLOCK_NODUMP flag > (suggested by Rob) instead of the v4 opt-in 'dumpable' flag on > DT-only struct reserved_mem. > > 2. Switch the riscv vmcore elf header preparation to use memblock > instead of the resource tree, aligning it with arm64 and loongarch, > so riscv also can exclude reserved memory from vmcore. > > 3. Deduplicate the vmcore elf header preparation: arm64, riscv and > loongarch open-coded the same logic, so fold it into shared > __weak defaults in crash_core. > > 4. Drop the v4 patch that saved /memreserve/ entries into the > reserved_mem array; /memreserve/ is now marked MEMBLOCK_NODUMP > directly. v5 looks much better, at least from the reserved memory regions perspective. > v3 --> v4: > 1. Rebase this series on v7.2-rc1. > 2. Add two cleanup patches (patch 02/03). > 3. Simplify patch 03 to avoid checking whether initial_boot_params is > NULL multiple times, suggested by Rob. > > v2 --> v3: > 1. Fix out-of-bounds issue if device tree lacks /reserved-memory node.[2] > 2. Fix UAF issue when alloc_reserved_mem_array() fails. > 3. Add some prepare patches. > > v1 --> v2: > 1. v1 added an opt-out DT property ('linux,no-dump'). Per Rob's > feedback [1], v2 drop that property and exclude reserve memory > by default. > 2. Split some prepared patches from the original patches. > 3. Address coding-style comments on patch 5 from Rob. > > [1] https://lore.kernel.org/lkml/20260506144542.GA2072596-robh@kernel.org/ > [2] https://protect2.fireeye.com/v1/url?k=05b72ed7-643c3bed-05b6a598-74fe4860008a-295907342918bd15&q=1&e=c408484d-fdd8-4fe4-8eee-690e883afb73&u=https%3A%2F%2Fsashiko.dev%2F%23%2Fpatchset%2F20260520091844.592753-1-chenwandun%2540lixiang.com%3Fpart%3D4 > > Wandun Chen (8): > memblock: introduce MEMBLOCK_NODUMP flag > of: reserved_mem: add dumpable flag to opt-in vmcore > of: reserved_mem: mark /reserved-memory entries with MEMBLOCK_NODUMP > of: reserved_mem: mark /memreserve/ entries as MEMBLOCK_NODUMP > riscv: build crash_mem ranges from memblock instead of resource tree > crash_core: fold duplicated memblock arch hooks into the weak default > crash_core: replace for_each_mem_range() with for_each_mem_region() > crash_core: skip MEMBLOCK_NODUMP regions when building vmcore ELF > header > > arch/arm64/kernel/machine_kexec_file.c | 29 ------------------ > arch/loongarch/kernel/machine_kexec_file.c | 27 ----------------- > arch/riscv/Kconfig | 2 +- > arch/riscv/kernel/machine_kexec_file.c | 33 -------------------- > drivers/of/fdt.c | 2 ++ > drivers/of/of_private.h | 1 + > drivers/of/of_reserved_mem.c | 35 ++++++++++++++++++++++ > include/linux/memblock.h | 9 ++++++ > include/linux/of_reserved_mem.h | 1 + > kernel/crash_core.c | 34 +++++++++++++++++++-- > kernel/dma/contiguous.c | 1 + > mm/memblock.c | 16 ++++++++++ > 12 files changed, 98 insertions(+), 92 deletions(-) > Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland