On Tue, Apr 26, 2022 at 07:15:06PM +0200, Vlastimil Babka wrote:
> On 4/14/22 10:57, Hyeonggon Yoo wrote:
> > Move tracepoints into kmalloc_large_node() and add missing flag fix code.
> >
> > Signed-off-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
>
Hello Vlastimil, thanks for review! ;-)
> Hm so there's a problem with the tracepoint's caller.
>
> kmalloc_large() is only called from kmalloc() which is an inline thus the
> callsite of kmalloc() calls directly kmalloc_large().
> So when kmalloc_large() does "trace_kmalloc(_RET_IP_, ...)" the _RET_IP_ is the
> callsite of kmalloc(), which is what we want.
kmalloc_large() had the exact problem before my series when called from __kmalloc().
On top of current slab/for-next:
[000] ..... 43.172574: kmalloc: call_site=__kmalloc+0x2aa/0x300 ptr=ffff88e2183a0000 bytes_req=12368 bytes_alloc=16384 gfp_flags=GFP_KERNEL
Considering different usecases of kmalloc_large_node() (called from kmalloc_node() or __kmalloc_node()),
I think we need trace/notrace version of kmalloc_large_node().
>
> But with kmalloc_large_node()...
>
> > ---
> > mm/slab_common.c | 6 ++++++
> > mm/slub.c | 22 ++++------------------
> > 2 files changed, 10 insertions(+), 18 deletions(-)
> >
> > diff --git a/mm/slab_common.c b/mm/slab_common.c
> > index e72089515030..cf17be8cd9ad 100644
> > --- a/mm/slab_common.c
> > +++ b/mm/slab_common.c
> > @@ -955,6 +955,9 @@ void *kmalloc_large_node(size_t size, gfp_t flags, int node)
> > void *ptr = NULL;
> > unsigned int order = get_order(size);
> >
> > + if (unlikely(flags & GFP_SLAB_BUG_MASK))
> > + flags = kmalloc_fix_flags(flags);
> > +
> > flags |= __GFP_COMP;
> > page = alloc_pages_node(node, flags, order);
> > if (page) {
> > @@ -966,6 +969,9 @@ void *kmalloc_large_node(size_t size, gfp_t flags, int node)
> > ptr = kasan_kmalloc_large(ptr, size, flags);
> > /* As ptr might get tagged, call kmemleak hook after KASAN. */
> > kmemleak_alloc(ptr, size, 1, flags);
> > + trace_kmalloc_node(_RET_IP_, ptr,
> > + size, PAGE_SIZE << order,
> > + flags, node);
>
> ... the _RET_IP_ here would be __kmalloc_node() which is not useful.
>
> > return ptr;
> > }
> > diff --git a/mm/slub.c b/mm/slub.c
> > index 640712706f2b..f10a892f1772 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -4396,15 +4396,8 @@ void *__kmalloc_node(size_t size, gfp_t flags, int node)
> > struct kmem_cache *s;
> > void *ret;
> >
> > - if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
> > - ret = kmalloc_large_node(size, flags, node);
> > -
> > - trace_kmalloc_node(_RET_IP_, ret,
> > - size, PAGE_SIZE << get_order(size),
> > - flags, node);
>
> Here it was OK because __kmalloc_node is expanded from something inline
> coming from slab.h.
>
> > -
> > - return ret;
> > - }
> > + if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
> > + return kmalloc_large_node(size, flags, node);
> >
> > s = kmalloc_slab(size, flags);
> >
> > @@ -4861,15 +4854,8 @@ void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
> > struct kmem_cache *s;
> > void *ret;
> >
> > - if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
> > - ret = kmalloc_large_node(size, gfpflags, node);
> > -
> > - trace_kmalloc_node(caller, ret,
> > - size, PAGE_SIZE << get_order(size),
> > - gfpflags, node);
> > -
> > - return ret;
> > - }
> > + if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
> > + return kmalloc_large_node(size, gfpflags, node);
>
> And here it even forgets the 'caller'.
>
Thanks for catching this.
I think notrace version + tracepoint would fit here.
> >
> > s = kmalloc_slab(size, gfpflags);
> >
>
--
Thanks,
Hyeonggon
