diff mbox series

[v3,08/35] mm: prevent slabobj_ext allocations for slabobj_ext and kmem_cache objects

Message ID 20240212213922.783301-9-surenb@google.com
State New
Headers
Series Memory allocation profiling |

Commit Message

Suren Baghdasaryan Feb. 12, 2024, 9:38 p.m. UTC 
  Use __GFP_NO_OBJ_EXT to prevent recursions when allocating slabobj_ext
objects. Also prevent slabobj_ext allocations for kmem_cache objects.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 mm/slab.h        | 6 ++++++
 mm/slab_common.c | 2 ++
 2 files changed, 8 insertions(+)

Comments

Kees Cook Feb. 12, 2024, 10:15 p.m. UTC | #1 
On Mon, Feb 12, 2024 at 01:38:54PM -0800, Suren Baghdasaryan wrote:
> Use __GFP_NO_OBJ_EXT to prevent recursions when allocating slabobj_ext
> objects. Also prevent slabobj_ext allocations for kmem_cache objects.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>

I almost feel like this can be collapsed into earlier patches, but
regardless:

Reviewed-by: Kees Cook <keescook@chromium.org>
Vlastimil Babka Feb. 15, 2024, 9:44 p.m. UTC | #2 
On 2/12/24 22:38, Suren Baghdasaryan wrote:
> Use __GFP_NO_OBJ_EXT to prevent recursions when allocating slabobj_ext
> objects. Also prevent slabobj_ext allocations for kmem_cache objects.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
>  mm/slab.h        | 6 ++++++
>  mm/slab_common.c | 2 ++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/mm/slab.h b/mm/slab.h
> index 436a126486b5..f4ff635091e4 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h
> @@ -589,6 +589,12 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
>  	if (!need_slab_obj_ext())
>  		return NULL;
>  
> +	if (s->flags & SLAB_NO_OBJ_EXT)
> +		return NULL;
> +
> +	if (flags & __GFP_NO_OBJ_EXT)
> +		return NULL;

Since we agreed to postpone this function, when it appears later it can have
those in.

>  	slab = virt_to_slab(p);
>  	if (!slab_obj_exts(slab) &&
>  	    WARN(alloc_slab_obj_exts(slab, s, flags, false),
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 6bfa1810da5e..83fec2dd2e2d 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -218,6 +218,8 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
>  	void *vec;
>  
>  	gfp &= ~OBJCGS_CLEAR_MASK;
> +	/* Prevent recursive extension vector allocation */
> +	gfp |= __GFP_NO_OBJ_EXT;

And this could become part of 6/35 mm: introduce __GFP_NO_OBJ_EXT ... ?

>  	vec = kcalloc_node(objects, sizeof(struct slabobj_ext), gfp,
>  			   slab_nid(slab));
>  	if (!vec)
Suren Baghdasaryan Feb. 15, 2024, 10:13 p.m. UTC | #3 
On Thu, Feb 15, 2024 at 1:44 PM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 2/12/24 22:38, Suren Baghdasaryan wrote:
> > Use __GFP_NO_OBJ_EXT to prevent recursions when allocating slabobj_ext
> > objects. Also prevent slabobj_ext allocations for kmem_cache objects.
> >
> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> > ---
> >  mm/slab.h        | 6 ++++++
> >  mm/slab_common.c | 2 ++
> >  2 files changed, 8 insertions(+)
> >
> > diff --git a/mm/slab.h b/mm/slab.h
> > index 436a126486b5..f4ff635091e4 100644
> > --- a/mm/slab.h
> > +++ b/mm/slab.h
> > @@ -589,6 +589,12 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
> >       if (!need_slab_obj_ext())
> >               return NULL;
> >
> > +     if (s->flags & SLAB_NO_OBJ_EXT)
> > +             return NULL;
> > +
> > +     if (flags & __GFP_NO_OBJ_EXT)
> > +             return NULL;
>
> Since we agreed to postpone this function, when it appears later it can have
> those in.

Yes, I think that works. Will have this in the same patch.

>
> >       slab = virt_to_slab(p);
> >       if (!slab_obj_exts(slab) &&
> >           WARN(alloc_slab_obj_exts(slab, s, flags, false),
> > diff --git a/mm/slab_common.c b/mm/slab_common.c
> > index 6bfa1810da5e..83fec2dd2e2d 100644
> > --- a/mm/slab_common.c
> > +++ b/mm/slab_common.c
> > @@ -218,6 +218,8 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
> >       void *vec;
> >
> >       gfp &= ~OBJCGS_CLEAR_MASK;
> > +     /* Prevent recursive extension vector allocation */
> > +     gfp |= __GFP_NO_OBJ_EXT;
>
> And this could become part of 6/35 mm: introduce __GFP_NO_OBJ_EXT ... ?

Yes, that will eliminate this patch. Thanks!

>
> >       vec = kcalloc_node(objects, sizeof(struct slabobj_ext), gfp,
> >                          slab_nid(slab));
> >       if (!vec)
>
diff mbox series

Patch

diff --git a/mm/slab.h b/mm/slab.h
index 436a126486b5..f4ff635091e4 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -589,6 +589,12 @@  prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
 	if (!need_slab_obj_ext())
 		return NULL;
 
+	if (s->flags & SLAB_NO_OBJ_EXT)
+		return NULL;
+
+	if (flags & __GFP_NO_OBJ_EXT)
+		return NULL;
+
 	slab = virt_to_slab(p);
 	if (!slab_obj_exts(slab) &&
 	    WARN(alloc_slab_obj_exts(slab, s, flags, false),
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 6bfa1810da5e..83fec2dd2e2d 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -218,6 +218,8 @@  int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
 	void *vec;
 
 	gfp &= ~OBJCGS_CLEAR_MASK;
+	/* Prevent recursive extension vector allocation */
+	gfp |= __GFP_NO_OBJ_EXT;
 	vec = kcalloc_node(objects, sizeof(struct slabobj_ext), gfp,
 			   slab_nid(slab));
 	if (!vec)