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[RFC,4/5] EXPERIMENTAL: x86: use __GFP_UNMAPPED for modele_alloc()

Message ID 20230308094106.227365-5-rppt@kernel.org (mailing list archive)
State New
Headers show
Series Prototype for direct map awareness in page allocator | expand

Commit Message

Mike Rapoport March 8, 2023, 9:41 a.m. UTC 
From: "Mike Rapoport (IBM)" <rppt@kernel.org>

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
---
 arch/x86/kernel/module.c | 2 +-
 mm/vmalloc.c             | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Comments

Edgecombe, Rick P March 9, 2023, 1:54 a.m. UTC | #1 
On Wed, 2023-03-08 at 11:41 +0200, Mike Rapoport wrote:
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index ef910bf349e1..84220ec45ec2 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2892,7 +2892,7 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
>          * to fails, fallback to a single page allocator that is
>          * more permissive.
>          */
> -       if (!order) {
> +       if (!order && !(gfp & __GFP_UNMAPPED)) {
>                 gfp_t bulk_gfp = gfp & ~__GFP_NOFAIL;
>  
>                 while (nr_allocated < nr_pages) {

This is obviously a quick POC patch, but I guess we should skip the
whole vm_remove_mappings() thing since it would reset the direct map to
RW for these unmapped pages. Or rather modules shouldn't set
VM_FLUSH_RESET_PERMS if it uses this.
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Patch

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 84ad0e61ba6e..845ed70ba5ab 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -67,7 +67,7 @@  static unsigned long int get_module_load_offset(void)
 
 void *module_alloc(unsigned long size)
 {
-	gfp_t gfp_mask = GFP_KERNEL;
+	gfp_t gfp_mask = GFP_KERNEL | __GFP_UNMAPPED;
 	void *p;
 
 	if (PAGE_ALIGN(size) > MODULES_LEN)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ef910bf349e1..84220ec45ec2 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2892,7 +2892,7 @@  vm_area_alloc_pages(gfp_t gfp, int nid,
 	 * to fails, fallback to a single page allocator that is
 	 * more permissive.
 	 */
-	if (!order) {
+	if (!order && !(gfp & __GFP_UNMAPPED)) {
 		gfp_t bulk_gfp = gfp & ~__GFP_NOFAIL;
 
 		while (nr_allocated < nr_pages) {