From: Wandun <chenwandun1@gmail.com>
To: Baoquan He <baoquan.he@linux.dev>
Cc: catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org,
pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu,
tglx@kernel.org, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, robh@kernel.org,
saravanak@kernel.org, akpm@linux-foundation.org, rppt@kernel.org,
pasha.tatashin@soleen.com, pratyush@kernel.org,
m.szyprowski@samsung.com, mark.rutland@arm.com,
kernel@xen0n.name, alex@ghiti.fr, hpa@zytor.com,
ruirui.yang@linux.dev, robin.murphy@arm.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, loongarch@lists.linux.dev,
linux-riscv@lists.infradead.org, devicetree@vger.kernel.org,
kexec@lists.infradead.org, linux-mm@kvack.org,
iommu@lists.linux.dev
Subject: Re: [PATCH v6 00/10] kdump: reduce vmcore size and capture time
Date: Fri, 18 Sep 2026 18:53:32 +0800 [thread overview]
Message-ID: <1a47d5de-fb68-4c10-a199-f0d274689cdc@gmail.com> (raw)
In-Reply-To: <aqzznOgILX2pZg7b@fedora>
On 9/18/26 16:17, Baoquan He wrote:
> On 09/02/26 at 03:31pm, Wandun Chen wrote:
>> From: Wandun Chen <chenwandun@lixiang.com>
>>
> ...snip...
>> 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
> ~~~
> The patchset itself looks goot to me, while I am concerned if it's
> really generic. I raised that in sub-thread talking with Wandun. Imagine
> I tried to exclude many driver regions and split memblock regions into
> hundreds, cma could yell out: cma_declare_contiguous_multi()?
Are you concerned that setting the MEMBLOCK_NODUMP flag could split a memblock
region into many smaller regions, which might then prevent
cma_declare_contiguous_multi() from satisfying a multi-range allocation?
If so, IICU I don’t think that applies here.
MEMBLOCK_NODUMP is currently only set on memory that has already been reserved.
These regions are excluded when iterating over free memory, so marking them NODUMP
does not increase the number of free regions seen by CMA.
Before marking NODUMP:
memblock.memory: [ free ] [ reserved ] [ free ]
memblock.reserved: [ reserved ]
Now, for memblock.memory, it is one region that contains free and reserved memory.
After marking the reserved region NODUMP:
memblock.memory: [ free ] [ NODUMP ] [ free ]
memblock.reserved: [ reserved ]
for memblock.memory, it splits into 3 regions, 2 free regions, 1 nodump region.
Although the memblock.memory array may be split internally, it does not create additional
free ranges for cma_declare_contiguous_multi() to process.
>
> IMHO, withdrawing the claim can fix the nit concern. If I am wrong,
> please help point it out to let me learn more.
I will revise this description to avoid any misunderstanding.
Best regards,
Wandun
>
> Thanks
> Baoquan
>
>> both ACPI and DT systems can benefit from it (suggested by Rob, thanks) [1].
>>
>> Since the reserved memory regions are filtered out, the vmcore is
>> smaller in size and faster to produce.
>>
> ...snip...
prev parent reply other threads:[~2026-09-18 10:53 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-02 7:31 Wandun Chen
2026-09-02 7:31 ` [PATCH v6 01/10] mm: memblock: add missing HugeTLB flag name Wandun Chen
2026-09-14 5:20 ` Mike Rapoport
2026-09-15 12:49 ` Wandun
2026-09-02 7:31 ` [PATCH v6 02/10] riscv: build crash_mem ranges from memblock instead of resource tree Wandun Chen
2026-09-02 7:31 ` [PATCH v6 03/10] crash_core: fold duplicated memblock arch hooks into the weak default Wandun Chen
2026-09-18 7:30 ` Baoquan He
2026-09-18 8:45 ` Wandun
2026-09-18 8:48 ` Baoquan He
2026-09-02 7:31 ` [PATCH v6 04/10] crash_core: serialize crash header preparation against hotplug Wandun Chen
2026-09-18 7:54 ` Baoquan He
2026-09-02 7:31 ` [PATCH v6 05/10] crash_core: replace for_each_mem_range() with for_each_mem_region() Wandun Chen
2026-09-18 8:04 ` Baoquan He
2026-09-02 7:31 ` [PATCH v6 06/10] memblock: introduce MEMBLOCK_NODUMP flag Wandun Chen
2026-09-18 7:00 ` Mike Rapoport
2026-09-18 8:08 ` Baoquan He
2026-09-18 8:22 ` Wandun
2026-09-02 7:31 ` [PATCH v6 07/10] of: reserved_mem: add dumpable flag to opt-in vmcore Wandun Chen
2026-09-17 21:56 ` Rob Herring (Arm)
2026-09-02 7:31 ` [PATCH v6 08/10] of: reserved_mem: mark /reserved-memory entries with MEMBLOCK_NODUMP Wandun Chen
2026-09-03 7:32 ` Marek Szyprowski
2026-09-17 21:56 ` Rob Herring (Arm)
2026-09-02 7:31 ` [PATCH v6 09/10] of: reserved_mem: mark /memreserve/ entries as MEMBLOCK_NODUMP Wandun Chen
2026-09-03 7:32 ` Marek Szyprowski
2026-09-02 7:31 ` [PATCH v6 10/10] crash_core: skip MEMBLOCK_NODUMP regions when building vmcore ELF header Wandun Chen
2026-09-18 8:09 ` Baoquan He
2026-09-02 8:53 ` [PATCH v6 00/10] kdump: reduce vmcore size and capture time Baoquan He
2026-09-03 7:05 ` Wandun
2026-09-03 7:31 ` Baoquan He
2026-09-03 7:43 ` Wandun
2026-09-03 9:38 ` Baoquan He
2026-09-04 11:08 ` Chen Wandun
2026-09-15 13:01 ` Wandun
2026-09-18 7:03 ` Mike Rapoport
2026-09-18 7:31 ` Baoquan He
2026-09-18 8:17 ` Baoquan He
2026-09-18 10:53 ` Wandun [this message]
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