On Sun, 10 May 2026 14:41:18 -0700 Rosen Penev <[email protected]> wrote:
> The XOL slot bitmap has the same lifetime as struct xol_area, but it > is currently allocated separately. That adds another allocation > failure path and a matching cleanup branch without buying any extra > flexibility. > > Store the bitmap as a flexible array member and allocate it together > with the xol_area using kzalloc_flex(). The bitmap remains > zero-initialized, while the allocation and error handling become > simpler. > You also have to update uprobe_clear_state(), because area->bitmap is no longer allocated separately. Thank you, > Assisted-by: Codex:GPT-5.5 > Signed-off-by: Rosen Penev <[email protected]> > --- > kernel/events/uprobes.c | 13 +++---------- > 1 file changed, 3 insertions(+), 10 deletions(-) > > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 4084e926e284..9ef74c2ad390 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -108,7 +108,6 @@ static LIST_HEAD(delayed_uprobe_list); > */ > struct xol_area { > wait_queue_head_t wq; /* if all slots are > busy */ > - unsigned long *bitmap; /* 0 = free slot */ > > struct page *page; > /* > @@ -117,6 +116,7 @@ struct xol_area { > * the vma go away, and we must handle that reasonably gracefully. > */ > unsigned long vaddr; /* Page(s) of > instruction slots */ > + unsigned long bitmap[]; /* 0 = free slot */ > }; > > static void uprobe_warn(struct task_struct *t, const char *msg) > @@ -1755,18 +1755,13 @@ static struct xol_area *__create_xol_area(unsigned > long vaddr) > struct xol_area *area; > void *insns; > > - area = kzalloc_obj(*area); > + area = kzalloc_flex(*area, bitmap, BITS_TO_LONGS(UINSNS_PER_PAGE)); > if (unlikely(!area)) > goto out; > > - area->bitmap = kcalloc(BITS_TO_LONGS(UINSNS_PER_PAGE), sizeof(long), > - GFP_KERNEL); > - if (!area->bitmap) > - goto free_area; > - > area->page = alloc_page(GFP_HIGHUSER | __GFP_ZERO); > if (!area->page) > - goto free_bitmap; > + goto free_area; > > area->vaddr = vaddr; > init_waitqueue_head(&area->wq); > @@ -1779,8 +1774,6 @@ static struct xol_area *__create_xol_area(unsigned long > vaddr) > return area; > > __free_page(area->page); > - free_bitmap: > - kfree(area->bitmap); > free_area: > kfree(area); > out: > -- > 2.54.0 > -- Masami Hiramatsu (Google) <[email protected]>
