On Mon, Jun 12, 2023 at 01:49:56PM +0200, Fabio M. De Francesco wrote: > On lunedì 12 giugno 2023 12:33:41 CEST Sumitra Sharma wrote: > > kmap() has been deprecated in favor of the kmap_local_page() > > due to high cost, restricted mapping space, the overhead of > > a global lock for synchronization, and making the process > > sleep in the absence of free slots. > > > > kmap_local_page() is faster than kmap() and offers thread-local > > and CPU-local mappings, take pagefaults in a local kmap region > > and preserves preemption by saving the mappings of outgoing > > tasks and restoring those of the incoming one during a context > > switch. > > > > The mapping is kept thread local in the function > > “generate_test_data” in test_bpf.c > > > > Therefore, replace kmap() with kmap_local_page() and use > > memcpy_to_page() to avoid open coding kmap_local_page() > > + memcpy() + kunmap_local(). > > > > Remove the unused variable “ptr”. > > Sumitra, > > Please Cc your mentors while in the internship. > It's not mandatory but it would expedite comments and reviews :-) > Hi Fabio, I will take care of it. > > > > Signed-off-by: Sumitra Sharma <sumitraartsy@xxxxxxxxx> > > --- > > lib/test_bpf.c | 10 +--------- > > 1 file changed, 1 insertion(+), 9 deletions(-) > > > > diff --git a/lib/test_bpf.c b/lib/test_bpf.c > > index ade9ac672adb..3bb94727d83b 100644 > > --- a/lib/test_bpf.c > > +++ b/lib/test_bpf.c > > @@ -14381,25 +14381,17 @@ static void *generate_test_data(struct bpf_test > > *test, int sub) * single fragment to the skb, filled with > > * test->frag_data. > > */ > > - void *ptr; > > - > > page = alloc_page(GFP_KERNEL); > > > > if (!page) > > goto err_kfree_skb; > > > > - ptr = kmap(page); > > - if (!ptr) > > - goto err_free_page; > > - memcpy(ptr, test->frag_data, MAX_DATA); > > - kunmap(page); > > + memcpy_to_page(page, 0, test->frag_data, MAX_DATA); > > Why are you temporary mapping a page allocated with the GFP_KERNEL flag? > It cannot come from ZONE_HIGHMEM. > Fabio, I somewhere _wrongly_ read that "GFP_KERNEL may allocate pages from highmem". However, with further readings and checking the GFP_KERNEL definition in gfp_types.h #define GFP_KERNEL (__GFP_RECLAIM | __GFP_IO | __GFP_FS) I have got that with the GFP_KERNEL flag, pages can never come from ZONE_HIGHMEM. Apologise. Thanks & regards Sumitra > Fabio > > > skb_add_rx_frag(skb, 0, page, 0, MAX_DATA, MAX_DATA); > > } > > > > return skb; > > > > -err_free_page: > > - __free_page(page); > > err_kfree_skb: > > kfree_skb(skb); > > return NULL; > > -- > > 2.25.1 > > >
