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Fri, 18 Sep 2026 01:22:20 -0700 (PDT) Message-ID: Date: Fri, 18 Sep 2026 16:22:03 +0800 Precedence: bulk X-Mailing-List: loongarch@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 06/10] memblock: introduce MEMBLOCK_NODUMP flag To: Baoquan He 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 References: <20260902073116.802752-1-chenwandun1@gmail.com> <20260902073116.802752-7-chenwandun1@gmail.com> Content-Language: en-US From: Wandun In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/18/26 16:08, Baoquan He wrote: > On 09/02/26 at 03:31pm, Wandun Chen wrote: >> From: Wandun Chen >> >> Add MEMBLOCK_NODUMP to mark regions that should be excluded from >> kdump vmcores. >> >> The flag is meant for reserved memory that carries no data useful for >> crash analysis. Reusable reserved regions such as CMA may hold useful >> data, so these regions must not be marked MEMBLOCK_NODUMP. Subsequent >> patches wire this up for /reserved-memory and /memreserve/ entries. >> >> Suggested-by: Rob Herring >> Signed-off-by: Wandun Chen >> Tested-by: Meijing Zhao >> --- >> include/linux/memblock.h | 9 +++++++++ >> mm/memblock.c | 16 ++++++++++++++++ >> 2 files changed, 25 insertions(+) >> >> diff --git a/include/linux/memblock.h b/include/linux/memblock.h >> index d62db9e776cf..b2fcf11fba2b 100644 >> --- a/include/linux/memblock.h >> +++ b/include/linux/memblock.h >> @@ -52,6 +52,8 @@ extern unsigned long long max_possible_pfn; >> * kernel that we know is good to use. It is the only memory that >> * allocations may happen from in this phase. >> * @MEMBLOCK_RSRV_HUGETLB: memory is reserved for hugetlb pages >> + * @MEMBLOCK_NODUMP: exclude from kdump vmcore. It carries no data useful >> + * for crash analysis (e.g. firmware carveouts). >> */ >> enum memblock_flags { >> MEMBLOCK_NONE = 0x0, /* No special request */ >> @@ -63,6 +65,7 @@ enum memblock_flags { >> MEMBLOCK_RSRV_KERN = 0x20, /* memory reserved for kernel use */ >> MEMBLOCK_KHO_SCRATCH = 0x40, /* scratch memory for kexec handover */ >> MEMBLOCK_RSRV_HUGETLB = 0x80, /* memory reserved for hugetlb pages */ >> + MEMBLOCK_NODUMP = 0x100,/* exclude from kdump vmcore */ >> }; >> >> /** >> @@ -160,6 +163,7 @@ int memblock_reserved_mark_noinit(phys_addr_t base, phys_addr_t size); >> int memblock_reserved_mark_kern(phys_addr_t base, phys_addr_t size); >> int memblock_mark_kho_scratch(phys_addr_t base, phys_addr_t size); >> int memblock_clear_kho_scratch(phys_addr_t base, phys_addr_t size); >> +int memblock_mark_nodump(phys_addr_t base, phys_addr_t size); >> >> void memblock_free(void *ptr, size_t size); >> void reset_all_zones_managed_pages(void); >> @@ -306,6 +310,11 @@ static inline bool memblock_is_kho_scratch(struct memblock_region *m) >> return m->flags & MEMBLOCK_KHO_SCRATCH; >> } >> >> +static inline bool memblock_is_nodump(struct memblock_region *m) >> +{ >> + return m->flags & MEMBLOCK_NODUMP; >> +} >> + >> int memblock_search_pfn_nid(unsigned long pfn, unsigned long *start_pfn, >> unsigned long *end_pfn); >> void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn, >> diff --git a/mm/memblock.c b/mm/memblock.c >> index f2952d725c10..2e87f39826dd 100644 >> --- a/mm/memblock.c >> +++ b/mm/memblock.c >> @@ -1204,6 +1204,21 @@ __init int memblock_clear_kho_scratch(phys_addr_t base, phys_addr_t size) >> MEMBLOCK_KHO_SCRATCH); >> } >> >> +/** >> + * memblock_mark_nodump - Mark a memory region with flag MEMBLOCK_NODUMP. >> + * @base: the base phys addr of the region >> + * @size: the size of the region >> + * >> + * Mark the region as not to be included in crash dumps. >> + * >> + * Return: 0 on success, -errno on failure. >> + */ >> +int __init_memblock memblock_mark_nodump(phys_addr_t base, phys_addr_t size) > ~~~~~~~~~~~~~~^ > Is it impossible to use at runtime even thought it claims to be generic? It is currently only used during initialization, so I added __init_memblock. If other modules need to use this function in the future, this annotation can be removed. Best regards, Wandun> > >> +{ >> + return memblock_setclr_flag(&memblock.memory, base, size, 1, >> + MEMBLOCK_NODUMP); >> +} >> + >> static bool should_skip_region(struct memblock_type *type, >> struct memblock_region *m, >> int nid, int flags) >> @@ -2887,6 +2902,7 @@ static const char * const flagname[] = { >> [ilog2(MEMBLOCK_RSRV_KERN)] = "RSV_KERN", >> [ilog2(MEMBLOCK_KHO_SCRATCH)] = "KHO_SCRATCH", >> [ilog2(MEMBLOCK_RSRV_HUGETLB)] = "RSV_HUGETLB", >> + [ilog2(MEMBLOCK_NODUMP)] = "NODUMP", >> }; >> >> static int memblock_debug_show(struct seq_file *m, void *private) >> -- >> 2.43.0 >>