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charset=us-ascii Content-Disposition: inline In-Reply-To: <8d1c6b04-105e-4fb2-b514-1c5dea0fcce6@arm.com> X-Rspamd-Queue-Id: 78757100021 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 7z8c9wint9owtx3pmap19g5nxb4oti93 X-HE-Tag: 1706528554-902067 X-HE-Meta: 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 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 Mon, Jan 29, 2024 at 01:49:44PM +0530, Anshuman Khandual wrote: > > > On 1/25/24 22:12, Alexandru Elisei wrote: > > The arm64 MTE code 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() by doing: > > > > page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; > > > > When tag storage management is added, tag storage will be reserved for a > > page if and only if the page is mapped as tagged (the page flag > > PG_mte_tagged is set). When a page is freed, likewise, the code will have > > to look at the the page flags to determine if the page has tag storage > > reserved, which should also be freed. > > > > For this purpose, add an arch_free_pages_prepare() hook that is called > > before that page flags are cleared. The function arch_free_page() has also > > been considered for this purpose, but it is called after the flags are > > cleared. > > arch_free_pages_prepare() makes sense as a prologue to arch_free_page(). Thanks! > > s/arch_free_pages_prepare/arch_free_page_prepare to match similar functions. The function free_pages_prepare() calls the function arch_free_pages_prepare(). I find that consistent, and it makes it easy to identify from where arch_free_pages_prepare() is called. Thanks, Alex > > > > > Signed-off-by: Alexandru Elisei > > --- > > > > Changes since rfc v2: > > > > * Expanded commit message (David Hildenbrand). > > > > include/linux/pgtable.h | 4 ++++ > > mm/page_alloc.c | 1 + > > 2 files changed, 5 insertions(+) > > > > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h > > index f6d0e3513948..6d98d5fdd697 100644 > > --- a/include/linux/pgtable.h > > +++ b/include/linux/pgtable.h > > @@ -901,6 +901,10 @@ static inline void arch_do_swap_page(struct mm_struct *mm, > > } > > #endif > > > > +#ifndef __HAVE_ARCH_FREE_PAGES_PREPARE > > I guess new __HAVE_ARCH_ constructs are not being added lately. Instead > something like '#ifndef arch_free_pages_prepare' might be better suited. > > > +static inline void arch_free_pages_prepare(struct page *page, int order) { } > > +#endif > > + > > #ifndef __HAVE_ARCH_UNMAP_ONE > > /* > > * Some architectures support metadata associated with a page. When a > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 2c140abe5ee6..27282a1c82fe 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1092,6 +1092,7 @@ static __always_inline bool free_pages_prepare(struct page *page, > > > > trace_mm_page_free(page, order); > > kmsan_free_page(page, order); > > + arch_free_pages_prepare(page, order); > > > > if (memcg_kmem_online() && PageMemcgKmem(page)) > > __memcg_kmem_uncharge_page(page, order);