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charset=us-ascii Content-Disposition: inline In-Reply-To: <45466b05-d620-41e5-8a2b-05c420b8fa7b@redhat.com> X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: F05E3180054 X-Stat-Signature: wadhbcfwx46otfkpe9kz6g9zn1z8yxmi X-HE-Tag: 1701090193-295047 X-HE-Meta: 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 RDC8j0S0 KhbpWN0xjHvKx4g1E8xqmsxW8YRWbpWz6khIjeKGWqrwDOcnvzXWpb53/QCuAj2em7sBanzM90cjSmj55qPtbwWaxrGE+ckb3G8hQl1YzcsNa2TccykhQJHJbRbqo0vKrrmMk6DGqyDnfwPyYnkSrtUTLhw== 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: Hi, On Fri, Nov 24, 2023 at 08:36:52PM +0100, David Hildenbrand wrote: > On 19.11.23 17:57, Alexandru Elisei wrote: > > Add arch_free_pages_prepare() hook that is called before that page flags > > are cleared. This will be used by arm64 when explicit management of tag > > storage pages is enabled. > > Can you elaborate a bit what exactly will be done by that code with that > information? Of course. The MTE code that is in the kernel today uses the PG_arch_2 page flag, which it renames to PG_mte_tagged, to track if a page has been mapped with tagging enabled. That flag is cleared by free_pages_prepare() when it does: page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; When tag storage management is enabled, tag storage is reserved for a page if and only if the page is mapped as tagged. When a page is freed, the code looks at the PG_mte_tagged flag to determine if the page was mapped as tagged, and therefore has tag storage reserved, to determine if the corresponding tag storage should also be freed. I have considered using arch_free_page(), but free_pages_prepare() calls the function after the flags are cleared. Does that answer your question? Alex > > -- > Cheers, > > David / dhildenb >