Re: [PATCH v2 2/2] mm/vmalloc: Print a warning message first on failure

Uladzislau Rezki
2021-05-09T20:05:35Z

On Sun, May 09, 2021 at 08:47:12PM +0100, Matthew Wilcox wrote:
> On Sun, May 09, 2021 at 09:38:44PM +0200, Uladzislau Rezki (Sony) wrote:
> > export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
> > - -O2 -fomit-frame-pointer -std=gnu89
> > + -O0 -g -fomit-frame-pointer -std=gnu89
>
> You clearly didn't intend to submit this portion ...
>
I sent a v3 that does not include it. That was added accidentally.

> > +++ b/mm/vmalloc.c
> > @@ -2781,11 +2781,11 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
> > }
> >
> > if (!area->pages) {
> > - free_vm_area(area);
> > warn_alloc(gfp_mask, NULL,
> > "vmalloc size %lu allocation failure: "
> > "page array size %lu allocation failed",
> > nr_small_pages * PAGE_SIZE, array_size);
> > + free_vm_area(area);
> > return NULL;
> > }
>
> I think this is a bad idea. We're clearly low on memory (a memory
> allocation just failed). We should free the memory we have allocated
> to improve the chances of the warning message making it out.
Not sure if i fully follow you here. We do free the memory. The intention
was to print a warning message first because, if, potentially, the
free_vm_area(area) also does some prints it would be a bit messy from the
point what has been broken first.

So, could you please clarify what was your concern?

--
Vlad Rezki