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Tue, 31 Mar 2026 10:44:53 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Tue, 31 Mar 2026 19:44:51 +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 v8 1/6] mm/vmalloc: extract vm_area_free_pages() helper from vfree() Message-ID: References: <20260327-vmalloc-shrink-v8-0-cc6b57059ed7@zohomail.in> <20260327-vmalloc-shrink-v8-1-cc6b57059ed7@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: <20260327-vmalloc-shrink-v8-1-cc6b57059ed7@zohomail.in> On Fri, Mar 27, 2026 at 03:18:37PM +0530, Shivam Kalra via B4 Relay wrote: > From: Shivam Kalra > > Extract the page-freeing loop 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). > > Reviewed-by: Alice Ryhl > Signed-off-by: Shivam Kalra > --- > mm/vmalloc.c | 47 +++++++++++++++++++++++++++++++++-------------- > 1 file changed, 33 insertions(+), 14 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index d75151649c97..79a57955345d 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3416,6 +3416,38 @@ 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; > + > + for (i = start_idx; i < end_idx; i++) { > + struct page *page = vm->pages[i]; > + > + BUG_ON(!page); > + /* > + * High-order allocs for huge vmallocs are split, so > + * can be freed as an array of order-0 allocations > + */ > + if (!(vm->flags & VM_MAP_PUT_PAGES)) > + mod_lruvec_page_state(page, NR_VMALLOC, -1); > + __free_page(page); > + vm->pages[i] = NULL; > + cond_resched(); > + } > +} > + > /** > * vfree - Release memory allocated by vmalloc() > * @addr: Memory base address > @@ -3436,7 +3468,6 @@ void vfree_atomic(const void *addr) > void vfree(const void *addr) > { > struct vm_struct *vm; > - int i; > > if (unlikely(in_interrupt())) { > vfree_atomic(addr); > @@ -3459,19 +3490,7 @@ void vfree(const void *addr) > > if (unlikely(vm->flags & VM_FLUSH_RESET_PERMS)) > vm_reset_perms(vm); > - for (i = 0; i < vm->nr_pages; i++) { > - struct page *page = vm->pages[i]; > - > - BUG_ON(!page); > - /* > - * High-order allocs for huge vmallocs are split, so > - * can be freed as an array of order-0 allocations > - */ > - if (!(vm->flags & VM_MAP_PUT_PAGES)) > - mod_lruvec_page_state(page, NR_VMALLOC, -1); > - __free_page(page); > - cond_resched(); > - } > + vm_area_free_pages(vm, 0, vm->nr_pages); > kvfree(vm->pages); > kfree(vm); > } > > -- > 2.43.0 > > Reviewed-by: Uladzislau Rezki (Sony) -- Uladzislau Rezki