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Wed, 06 May 2026 11:32:35 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Wed, 6 May 2026 20:32:33 +0200 To: shivamkalra98@zohomail.in Cc: Andrew Morton , Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Alice Ryhl , Danilo Krummrich Subject: Re: [PATCH v12 1/5] mm/vmalloc: extract vm_area_free_pages() helper from vfree() Message-ID: References: <20260428-vmalloc-shrink-v12-0-3c18c9172eb1@zohomail.in> <20260428-vmalloc-shrink-v12-1-3c18c9172eb1@zohomail.in> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260428-vmalloc-shrink-v12-1-3c18c9172eb1@zohomail.in> On Tue, Apr 28, 2026 at 01:54:16AM +0530, Shivam Kalra via B4 Relay wrote: > From: Shivam Kalra > > Extract page freeing and NR_VMALLOC stat accounting from > vfree() into a reusable vm_area_free_pages() helper. > The helper operates on a range [start_idx, end_idx) of pages > from a vm_struct, making it suitable for both full free (vfree) > and partial free (upcoming vrealloc shrink). > > Freed page pointers in vm->pages[] are set to NULL > to prevent stale references when the vm_struct outlives the > free (as in vrealloc shrink). > > Signed-off-by: Shivam Kalra > --- > mm/vmalloc.c | 34 +++++++++++++++++++++++++++------- > 1 file changed, 27 insertions(+), 7 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 878c5b7bf837..1073abb6094e 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3416,6 +3416,32 @@ void vfree_atomic(const void *addr) > schedule_work(&p->wq); > } > > +/* > + * vm_area_free_pages - free a range of pages from a vmalloc allocation > + * @vm: the vm_struct containing the pages > + * @start_idx: first page index to free (inclusive) > + * @end_idx: last page index to free (exclusive) > + * > + * Free pages [start_idx, end_idx) updating NR_VMALLOC stat accounting. > + * Freed vm->pages[] entries are set to NULL. > + * Caller is responsible for unmapping (vunmap_range) and KASAN > + * poisoning before calling this. > + */ > +static void vm_area_free_pages(struct vm_struct *vm, unsigned int start_idx, > + unsigned int end_idx) > +{ > + unsigned int i; > + > + if (!(vm->flags & VM_MAP_PUT_PAGES)) { > + for (i = start_idx; i < end_idx; i++) > + mod_lruvec_page_state(vm->pages[i], NR_VMALLOC, -1); > + } > + free_pages_bulk(vm->pages + start_idx, end_idx - start_idx); > + > + for (i = start_idx; i < end_idx; i++) > + vm->pages[i] = NULL; > +} > + > /** > * vfree - Release memory allocated by vmalloc() > * @addr: Memory base address > @@ -3436,7 +3462,6 @@ void vfree_atomic(const void *addr) > void vfree(const void *addr) > { > struct vm_struct *vm; > - int i; > > if (unlikely(in_interrupt())) { > vfree_atomic(addr); > @@ -3460,12 +3485,7 @@ void vfree(const void *addr) > if (unlikely(vm->flags & VM_FLUSH_RESET_PERMS)) > vm_reset_perms(vm); > > - if (!(vm->flags & VM_MAP_PUT_PAGES)) { > - for (i = 0; i < vm->nr_pages; i++) > - mod_lruvec_page_state(vm->pages[i], NR_VMALLOC, -1); > - } > - free_pages_bulk(vm->pages, vm->nr_pages); > - > + vm_area_free_pages(vm, 0, vm->nr_pages); > kvfree(vm->pages); > kfree(vm); > } > > -- > 2.43.0 > > Reviewed-by: Uladzislau Rezki (Sony) -- Uladzislau Rezki