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charset=us-ascii Content-Disposition: inline In-Reply-To: <17dabd83-0849-44c9-b4a2-196af60d9676@redhat.com> X-Rspamd-Queue-Id: 87ED740008 X-Stat-Signature: ebdo4p8wksnkeqig136n36njjjnxj39h X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1758706566-416769 X-HE-Meta: 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 T2n4WFgy rsb0fzAaHK19FUXD9jBIv+NDRH/qdP1b2i/xJkZPfW9Lyd3zZViFquZC/Y11ZOkwI0KYlKm0FNSMM2FHRIIxPHotm5MeL6bs+Aqz1/R6jbKSJ6ItEr68pv28m9BXcRDqA3v9xVm9yXzFnax72JqWdi6qX2qUclYndyaMrWZntVUcsAwnQuSff9lUYnDFxKgVxeoo5wvmhK+VV/DV4mSeXAOVzpPyAWw7OygCKWdw2NYZR4Xp9VaBVDB4MfZhiMquC4QQ1vLes0qpcJ12oZxuWMf08D9eGxt/n17GxIElcMZTeQpkOWgRStKT5jWmY+baAQK7wTaY+RfLIjufZoRganpsTGJm1uo7usDJwgG9bGA7h9iXP3NwD6vnOLJrcKwOQcLjO1FRjHVo4LUGgCw6A9n98TBh3aeCV/x8P 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 Wed, Sep 24, 2025 at 11:13:18AM +0200, David Hildenbrand wrote: > On 24.09.25 10:50, Catalin Marinas wrote: > > On Wed, Sep 24, 2025 at 10:49:27AM +0800, Lance Yang wrote: > > > On 2025/9/24 00:14, Catalin Marinas wrote: > > > > So alternative patch that also fixes the deferred struct page init (on > > > > the assumptions that the zero page is always mapped as pte_special(): > > > > > > I can confirm that this alternative patch also works correctly; my tests > > > for MTE all pass ;) > > > > Thanks Lance for testing. I'll post one of the variants today. > > > > > This looks like a better fix since it solves the boot hang issue too. > > > > In principle, yes, until I tracked down why I changed it in the first > > place - 68d54ceeec0e ("arm64: mte: Allow PTRACE_PEEKMTETAGS access to > > the zero page"). ptrace() can read tags from PROT_MTE mappings and we > > want to allow reading zeroes as well if the page points to the zero > > page. Not flagging the page as PG_mte_tagged caused issues. > > > > I can change the logic in the ptrace() code, I just need to figure out > > what happens to the huge zero page. Ideally we should treat both in the > > same way but, AFAICT, we don't use pmd_mkspecial() on the huge zero > > page, so it gets flagged with PG_mte_tagged. > > I changed that recently :) The huge zero folio will now always have > pmd_special() set. Oh, which commit was this? It means that we can end up with uninitialised tags if we have a PROT_MTE huge zero page since set_pmd_at/set_pte_at() skips mte_sync_tags(). -- Catalin