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charset=us-ascii Content-Disposition: inline In-Reply-To: <20231012013505.GB2426387@tiffany> X-Stat-Signature: iqj8umbi7ugd7xz4ur83by8od6a3hyed X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: EC6DE4001E X-Rspam-User: X-HE-Tag: 1697460110-334239 X-HE-Meta: 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 S41I872F uvRTxwy146sh6FNqBrNymCc68zF4tkya0K/cghBibYfyCK+h90kFCi4m87QLvcjAkICCi15zsYAJYWUmOA8oxhXe6nozFGD8ZksJeWTa5nZX/NejyOyWaN9smvjcbkKi1LfBFMbeKuG+kPUzMmkkEgtIUEPkdg2f+1N78 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: Hi, On Thu, Oct 12, 2023 at 10:35:05AM +0900, Hyesoo Yu wrote: > On Wed, Aug 23, 2023 at 02:13:30PM +0100, Alexandru Elisei wrote: > > Reserving the tag storage associated with a tagged page requires the > > ability to migrate existing data if the tag storage is in use for data. > > > > The kernel allocates pages, which are now tagged because of HW KASAN, in > > non-preemptible contexts, which can make reserving the associate tag > > storage impossible. > > > > Don't expose the tag storage pages to the memory allocator if HW KASAN is > > enabled. > > > > Signed-off-by: Alexandru Elisei > > --- > > arch/arm64/kernel/mte_tag_storage.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/arch/arm64/kernel/mte_tag_storage.c b/arch/arm64/kernel/mte_tag_storage.c > > index 4a6bfdf88458..f45128d0244e 100644 > > --- a/arch/arm64/kernel/mte_tag_storage.c > > +++ b/arch/arm64/kernel/mte_tag_storage.c > > @@ -314,6 +314,18 @@ static int __init mte_tag_storage_activate_regions(void) > > return 0; > > } > > > > + /* > > + * The kernel allocates memory in non-preemptible contexts, which makes > > + * migration impossible when reserving the associated tag storage. > > + * > > + * The check is safe to make because KASAN HW tags are enabled before > > + * the rest of the init functions are called, in smp_prepare_boot_cpu(). > > + */ > > + if (kasan_hw_tags_enabled()) { > > + pr_info("KASAN HW tags enabled, disabling tag storage"); > > + return 0; > > + } > > + > > Hi. > > Is there no plan to enable HW KASAN in the current design ? > I wonder if dynamic MTE is only used for user ? The tag storage pages are exposed to the page allocator if and only if HW KASAN is disabled: static int __init mte_tag_storage_activate_regions(void) [..] /* * The kernel allocates memory in non-preemptible contexts, which makes * migration impossible when reserving the associated tag storage. * * The check is safe to make because KASAN HW tags are enabled before * the rest of the init functions are called, in smp_prepare_boot_cpu(). */ if (kasan_hw_tags_enabled()) { pr_info("KASAN HW tags enabled, disabling tag storage"); return 0; } No plans at the moment to have this series compatible with HW KASAN. I will revisit this if/when the series gets merged. Thanks, Alex > > Thanks, > Hyesoo Yu. > > > > for (i = 0; i < num_tag_regions; i++) { > > tag_range = &tag_regions[i].tag_range; > > for (pfn = tag_range->start; pfn <= tag_range->end; pfn += pageblock_nr_pages) { > > -- > > 2.41.0 > > > >