linux-kernel - Re: [PATCH 2/3] mm, slub: don't combine pr

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Date:   Thu, 28 Jan 2021 21:06:09 +0800
From:   Yafang Shao <laoar.shao@...il.com>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     David Hildenbrand <david@...hat.com>,
        Christoph Lameter <cl@...ux.com>, penberg@...nel.org,
        David Rientjes <rientjes@...gle.com>, iamjoonsoo.kim@....com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        andriy.shevchenko@...ux.intel.com,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] mm, slub: don't combine pr_err with INFO

On Thu, Jan 28, 2021 at 6:35 PM Vlastimil Babka <vbabka@...e.cz> wrote:
>
> On 1/28/21 3:19 AM, Yafang Shao wrote:
> > It is strange to combine "pr_err" with "INFO", so let's clean them up.
> > This patch is motivated by David's comment[1].
> >
> > - before the patch
> > [ 8846.517809] INFO: Slab 0x00000000f42a2c60 objects=33 used=3 fp=0x0000000060d32ca8 flags=0x17ffffc0010200(slab|head)
> >
> > - after the patch
> > [ 6312.639698] ERR: Slab 0x000000006d1133b9 objects=33 used=3 fp=0x000000006d0779d1 flags=0x17ffffc0010200(slab|head)
> >
> > [1]. https://lore.kernel.org/linux-mm/b9c0f2b6-e9b0-0c36-ebdd-2bc684c5a762@redhat.com/#t
> >
> > Cc: David Hildenbrand <david@...hat.com>
> > Signed-off-by: Yafang Shao <laoar.shao@...il.com>
>
> These are usually printed as part of slab_bug() with its prominent banner. In
> that sense it's additional details, thus INFO. The details itself are not error,
> thus ERR makes little sense imho. How about removing the prefix completely, or
> just replacing with an ident to make it visually part of the BUG report.
>

Thanks for the explanation. I will remove the prefix completely in the
next version.

> > ---
> >  mm/slub.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/mm/slub.c b/mm/slub.c
> > index 4b9ab267afbc..18b4474c8fa2 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -615,7 +615,7 @@ static void print_track(const char *s, struct track *t, unsigned long pr_time)
> >       if (!t->addr)
> >               return;
> >
> > -     pr_err("INFO: %s in %pS age=%lu cpu=%u pid=%d\n",
> > +     pr_err("ERR: %s in %pS age=%lu cpu=%u pid=%d\n",
> >              s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid);
> >  #ifdef CONFIG_STACKTRACE
> >       {
> > @@ -641,7 +641,7 @@ void print_tracking(struct kmem_cache *s, void *object)
> >
> >  static void print_page_info(struct page *page)
> >  {
> > -     pr_err("INFO: Slab 0x%p objects=%u used=%u fp=0x%p flags=%#lx(%pGp)\n",
> > +     pr_err("ERR: Slab 0x%p objects=%u used=%u fp=0x%p flags=%#lx(%pGp)\n",
> >              page, page->objects, page->inuse, page->freelist,
> >              page->flags, &page->flags);
> >
> > @@ -698,7 +698,7 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
> >
> >       print_page_info(page);
> >
> > -     pr_err("INFO: Object 0x%p @offset=%tu fp=0x%p\n\n",
> > +     pr_err("ERR: Object 0x%p @offset=%tu fp=0x%p\n\n",
> >              p, p - addr, get_freepointer(s, p));
> >
> >       if (s->flags & SLAB_RED_ZONE)
> > @@ -791,7 +791,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
> >               end--;
> >
> >       slab_bug(s, "%s overwritten", what);
> > -     pr_err("INFO: 0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n",
> > +     pr_err("ERR: 0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n",
> >                                       fault, end - 1, fault - addr,
> >                                       fault[0], value);
> >       print_trailer(s, page, object);
> > @@ -3855,7 +3855,7 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page,
> >       for_each_object(p, s, addr, page->objects) {
> >
> >               if (!test_bit(__obj_to_index(s, addr, p), map)) {
> > -                     pr_err("INFO: Object 0x%p @offset=%tu\n", p, p - addr);
> > +                     pr_err("ERR: Object 0x%p @offset=%tu\n", p, p - addr);
> >                       print_tracking(s, p);
> >               }
> >       }
> >
>


-- 
Thanks
Yafang