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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Stat-Signature: kjmimzeohy6gqffy13ez5o3o579dhexi X-Rspam-User: X-Rspamd-Queue-Id: C56AF1C0010 X-HE-Tag: 1771257215-880036 X-HE-Meta: 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 TJ4nHBJP 3Frj7qy/GQrbpOWG/8GWVNdC8DEG81pmT8o1J8te0nJO68xZJkAxCdB6A5HkXNft1cs7sgxhd4x4nbTod1hKTF+bcm3z4ASjQMotyxKa4PrIbKb8U0agiEh43YiUi8Arf5PZ6fw1lQ9/JAzbL6hMvqZBtY5Egx6FqZpLR/WRuzwttrBlBitzUAA2ER+iL55Fmd6Wpd+36wBaAvEqCYj5VtgtQ1wFR3QvBmN5g X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/14/26 07:51, Mike Rapoport wrote: > Heh, it's x86's choice of memblock iterator that's rounding the ranges 😉 Ahh, good point. I was just assuming that the memblock iteration _had_ to be over PFNs. Silly me. > Maybe I miss some context, but my understanding is that for crash kernels > the unaccepted table is E820_TYPE_RESERVED and those are never added to > memblock.memory by e820 code, hence the call to memblock_add() in > reserve_unaccepted(). > > When x86 creates page tables, init_range_memory_mapping() walks > memblock.memory with for_each_mem_pfn_range() that rounds ranges that are > not page-aligned, which is normally fine, because it would mean that we > miss some partial pages that are divided between E820_RAM and > E820_SOMETHING_ELSE. > > And Kiryl's intention to round up unaccepted to page boundary seems correct > to me. It fixes the bug for sure. I'm more worried about the next feature, or the existing features that also only working because memory is page-aligned somewhere (even though it isn't guaranteed to remain that way). There are two choices for fixing this: One, we do Kiryl's fix plus checks to ensure that all the memblocks that generate direct mappings (is it _just_ the "memory" type?) are padded out to page-aligned boundaries. The other alternative is to do for_each_mem_range() and do the padding universally when creating the mappings. Maybe _also_ with warnings or maybe a pr_debug(). I do still think it's a little wonky for memblock_add()'s management of the "memory" type to allow unaligned arguments when that type is also used to create page-aligned mapping structures. Memblocks themselves obviously need to be byte-level, but I'm not sure it's the right thing for the "memory" type API.