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b=agYaSvIWAVylVBpeUol1lRZvfzrti5o8WbDuWlKrrwbYdr0dwifXMsGrmIlyHePPP YyUYx7bvkZkm3NTlCUatW5WC8//OOLmb1h4P0nJAivd0tC01YefT5+jBuSmxUBbIqx lZCAaSWFrJ0fDvQkeGy2oejHCSYrIfEcv0GdeWWvoahKvvdNSjO6ZPsRa/dzfDWMOU R4sKlrkEC1w/6ufKoK+qGN9pNIfWgnXU58YOp+kjC4eKv+SyXrav4Yupo1+/PZbdeE VCMOd+o3/AAkdy7vS8nsd9eHZR4xSq5YCOvLBnDvReNoEPVVnTWTUi+ghyJAG0Ew3f 0tqmc4P7eAPSA== Date: Wed, 29 Jul 2026 10:32:20 +0100 From: "Lorenzo Stoakes (ARM)" To: Yang Shi Cc: cl@gentwo.org, dennis@kernel.org, tj@kernel.org, urezki@gmail.com, catalin.marinas@arm.com, will@kernel.org, ryan.roberts@arm.com, david@kernel.org, akpm@linux-foundation.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 04/16] vmalloc: pass in pgd pointer for vmap{__vunmap}_range_noflush() Message-ID: References: <20260715180455.515692-1-yang@os.amperecomputing.com> <20260715180455.515692-5-yang@os.amperecomputing.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260715180455.515692-5-yang@os.amperecomputing.com> X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 3CB35140008 X-Stat-Signature: axhmej7omxjqf4q4pexiu3oj3p3ww6ap X-Rspam-User: X-HE-Tag: 1785317556-143696 X-HE-Meta: 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 uramKTR2 3aWNTkk896Eovc7BO6g6SUbY9/Rm41J6m9n50GC4rhgxMfZTB5954kONfIaZ4oHiK8WV8QcYH/NwhZbJE38IvKmqjLk/GAa/gJO7C4s7G+FgvJw0BY1leTIJbpiqG7YUZ4GmqNsSN/fhpoqWjgPX0Cc6uLG/1LL1ao2V7OWTVk+ppU6xH3BvavwBye8F8+sZpBOsf3+Bq9BeftuWzbP1IR01GMs+ZANa4RzNNHruXwyjtGwrdgGuYuJ3DJ356wFp5O9rgssA0Kztgr3ScoijaviQeMVLSOi20Ii6o9e3nRCjEjKYrdcwBDNEDastTptfCjI1zKCdyDJa5hV99Yw+IWtWFnYxGy+ovBllFejsn641VAto= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 15, 2026 at 11:04:06AM -0700, Yang Shi wrote: > vmap{__vunmap}_range_noflush() assume manipulate init_mm pgd. The It's not an assumption, it's a requirement. There is now (and really should have always been) strictly a locking requirement that the mm being manipulated is init_mm. > following patch will map percpu local mapping into percpu page table by > calling them, so the assumption will no longer stand. Make them take > pgd pointer as an parameter. No, this isn't OK. vmalloc is expressly for manipulating kernel mappings in init_mm. > > Also make vmap_range_noflush() non static, it will be called outside > vmalloc in the following patch. Hmm not loving the exposure of an internal function ehre. > > There is no functional change. > > Signed-off-by: Yang Shi You're fundamentally changing something here, conceptually. I'm not sure why you specifically need vmalloc to do it but it doesn't strike me as worthwhile for what you're doing. > --- > mm/internal.h | 5 ++++- > mm/kmsan/hooks.c | 14 +++++++------- > mm/vmalloc.c | 25 +++++++++++++------------ > 3 files changed, 24 insertions(+), 20 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index 181e79f1d6a2..9d9f08cb26a1 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -1552,10 +1552,13 @@ void clear_vm_uninitialized_flag(struct vm_struct *vm); > int __must_check __vmap_pages_range_noflush(unsigned long addr, > unsigned long end, pgprot_t prot, > struct page **pages, unsigned int page_shift); > +int __must_check vmap_range_noflush(pgd_t *pgdir, unsigned long addr, > + unsigned long end, phys_addr_t phys_addr, > + pgprot_t prot, unsigned int max_page_shift); > > void vunmap_range_noflush(unsigned long start, unsigned long end); > > -void __vunmap_range_noflush(unsigned long start, unsigned long end); > +void __vunmap_range_noflush(pgd_t *pgdir, unsigned long start, unsigned long end); > > static inline bool vma_is_single_threaded_private(struct vm_area_struct *vma) > { > diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c > index 8f22d1f22981..e2a0faf344b9 100644 > --- a/mm/kmsan/hooks.c > +++ b/mm/kmsan/hooks.c > @@ -135,8 +135,8 @@ static unsigned long vmalloc_origin(unsigned long addr) > > void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end) > { > - __vunmap_range_noflush(vmalloc_shadow(start), vmalloc_shadow(end)); > - __vunmap_range_noflush(vmalloc_origin(start), vmalloc_origin(end)); > + __vunmap_range_noflush(init_mm.pgd, vmalloc_shadow(start), vmalloc_shadow(end)); > + __vunmap_range_noflush(init_mm.pgd, vmalloc_origin(start), vmalloc_origin(end)); > flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end)); > flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end)); > } > @@ -181,7 +181,7 @@ int kmsan_ioremap_page_range(unsigned long start, unsigned long end, > vmalloc_origin(start + off + PAGE_SIZE), prot, &origin, > PAGE_SHIFT); > if (mapped) { > - __vunmap_range_noflush( > + __vunmap_range_noflush(init_mm.pgd, > vmalloc_shadow(start + off), > vmalloc_shadow(start + off + PAGE_SIZE)); > err = mapped; > @@ -203,10 +203,10 @@ int kmsan_ioremap_page_range(unsigned long start, unsigned long end, > __free_pages(shadow, 1); > if (origin) > __free_pages(origin, 1); > - __vunmap_range_noflush( > + __vunmap_range_noflush(init_mm.pgd, > vmalloc_shadow(start), > vmalloc_shadow(start + clean * PAGE_SIZE)); > - __vunmap_range_noflush( > + __vunmap_range_noflush(init_mm.pgd, > vmalloc_origin(start), > vmalloc_origin(start + clean * PAGE_SIZE)); > } > @@ -233,8 +233,8 @@ void kmsan_iounmap_page_range(unsigned long start, unsigned long end) > i++, v_shadow += PAGE_SIZE, v_origin += PAGE_SIZE) { > shadow = kmsan_vmalloc_to_page_or_null((void *)v_shadow); > origin = kmsan_vmalloc_to_page_or_null((void *)v_origin); > - __vunmap_range_noflush(v_shadow, vmalloc_shadow(end)); > - __vunmap_range_noflush(v_origin, vmalloc_origin(end)); > + __vunmap_range_noflush(init_mm.pgd, v_shadow, vmalloc_shadow(end)); > + __vunmap_range_noflush(init_mm.pgd, v_origin, vmalloc_origin(end)); > if (shadow) > __free_pages(shadow, 1); > if (origin) > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 1afca3568b9b..17c26e9796b2 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -295,9 +295,9 @@ static int vmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end, > return err; > } > > -static int vmap_range_noflush(unsigned long addr, unsigned long end, > - phys_addr_t phys_addr, pgprot_t prot, > - unsigned int max_page_shift) > +int vmap_range_noflush(pgd_t *pgdir, unsigned long addr, unsigned long end, > + phys_addr_t phys_addr, pgprot_t prot, > + unsigned int max_page_shift) > { > pgd_t *pgd; > unsigned long start; > @@ -314,7 +314,7 @@ static int vmap_range_noflush(unsigned long addr, unsigned long end, > BUG_ON(addr >= end); > > start = addr; > - pgd = pgd_offset_k(addr); > + pgd = pgd_offset_pgd(pgdir, addr); > do { > next = pgd_addr_end(addr, end); > err = vmap_p4d_range(pgd, addr, next, phys_addr, prot, > @@ -334,8 +334,8 @@ int vmap_page_range(unsigned long addr, unsigned long end, > { > int err; > > - err = vmap_range_noflush(addr, end, phys_addr, pgprot_nx(prot), > - ioremap_max_page_shift); > + err = vmap_range_noflush(init_mm.pgd, addr, end, phys_addr, > + pgprot_nx(prot), ioremap_max_page_shift); > flush_cache_vmap(addr, end); > if (!err) > err = kmsan_ioremap_page_range(addr, end, phys_addr, prot, > @@ -478,7 +478,7 @@ static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end, > * > * This is an internal function only. Do not use outside mm/. > */ > -void __vunmap_range_noflush(unsigned long start, unsigned long end) > +void __vunmap_range_noflush(pgd_t *pgdir, unsigned long start, unsigned long end) > { > unsigned long next; > pgd_t *pgd; > @@ -486,7 +486,7 @@ void __vunmap_range_noflush(unsigned long start, unsigned long end) > pgtbl_mod_mask mask = 0; > > BUG_ON(addr >= end); > - pgd = pgd_offset_k(addr); > + pgd = pgd_offset_pgd(pgdir, addr); > do { > next = pgd_addr_end(addr, end); > if (pgd_bad(*pgd)) > @@ -503,7 +503,7 @@ void __vunmap_range_noflush(unsigned long start, unsigned long end) > void vunmap_range_noflush(unsigned long start, unsigned long end) > { > kmsan_vunmap_range_noflush(start, end); > - __vunmap_range_noflush(start, end); > + __vunmap_range_noflush(init_mm.pgd, start, end); > } > > /** > @@ -670,9 +670,10 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end, > for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) { > int err; > > - err = vmap_range_noflush(addr, addr + (1UL << page_shift), > - page_to_phys(pages[i]), prot, > - page_shift); > + err = vmap_range_noflush(init_mm.pgd, addr, > + addr + (1UL << page_shift), > + page_to_phys(pages[i]), prot, > + page_shift); > if (err) > return err; > > -- > 2.47.0 > > > Cheers, Lorenzo