Re: FAILED: patch "[PATCH] mm: kfence: fix using kfence_metadata without initialization" failed to apply to 5.15-stable tree

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Mar 28, 2023 at 09:02:27PM +0800, Muchun Song wrote:
> 
> 
> On 2023/3/28 20:01, gregkh@linuxfoundation.org wrote:
> > The patch below does not apply to the 5.15-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> > 
> > To reproduce the conflict and resubmit, you may use the following commands:
> > 
> > git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
> > git checkout FETCH_HEAD
> > git cherry-pick -x 1c86a188e03156223a34d09ce290b49bd4dd0403
> > # <resolve conflicts, build, test, etc.>
> > git commit -s
> > git send-email --to '<stable@vger.kernel.org>' --in-reply-to '16800049118459@kroah.com' --subject-prefix 'PATCH 5.15.y' HEAD^..
> > 
> > Possible dependencies:
> > 
> > 1c86a188e031 ("mm: kfence: fix using kfence_metadata without initialization in show_object()")
> > b33f778bba5e ("kfence: alloc kfence_pool after system startup")
> > 698361bca2d5 ("kfence: allow re-enabling KFENCE after system startup")
> > 07e8481d3c38 ("kfence: always use static branches to guard kfence_alloc()")
> > 08f6b10630f2 ("kfence: limit currently covered allocations when pool nearly full")
> > a9ab52bbcb52 ("kfence: move saving stack trace of allocations into __kfence_alloc()")
> > 9a19aeb56650 ("kfence: count unexpectedly skipped allocations")
> > 
> > thanks,
> > 
> > greg k-h
> > 
> > ------------------ original commit in Linus's tree ------------------
> > 
> >  From 1c86a188e03156223a34d09ce290b49bd4dd0403 Mon Sep 17 00:00:00 2001
> > From: Muchun Song <muchun.song@linux.dev>
> > Date: Wed, 15 Mar 2023 11:44:41 +0800
> > Subject: [PATCH] mm: kfence: fix using kfence_metadata without initialization
> >   in show_object()
> > 
> > The variable kfence_metadata is initialized in kfence_init_pool(), then,
> > it is not initialized if kfence is disabled after booting.  In this case,
> > kfence_metadata will be used (e.g.  ->lock and ->state fields) without
> > initialization when reading /sys/kernel/debug/kfence/objects.  There will
> > be a warning if you enable CONFIG_DEBUG_SPINLOCK.  Fix it by creating
> > debugfs files when necessary.
> > 
> > Link: https://lkml.kernel.org/r/20230315034441.44321-1-songmuchun@bytedance.com
> > Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
> > Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> > Tested-by: Marco Elver <elver@google.com>
> > Reviewed-by: Marco Elver <elver@google.com>
> > Cc: Alexander Potapenko <glider@google.com>
> > Cc: Dmitry Vyukov <dvyukov@google.com>
> > Cc: Jann Horn <jannh@google.com>
> > Cc: SeongJae Park <sjpark@amazon.de>
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> > 
> > diff --git a/mm/kfence/core.c b/mm/kfence/core.c
> > index 5349c37a5dac..79c94ee55f97 100644
> > --- a/mm/kfence/core.c
> > +++ b/mm/kfence/core.c
> > @@ -726,10 +726,14 @@ static const struct seq_operations objects_sops = {
> >   };
> >   DEFINE_SEQ_ATTRIBUTE(objects);
> > -static int __init kfence_debugfs_init(void)
> > +static int kfence_debugfs_init(void)
> >   {
> > -	struct dentry *kfence_dir = debugfs_create_dir("kfence", NULL);
> > +	struct dentry *kfence_dir;
> > +	if (!READ_ONCE(kfence_enabled))
> > +		return 0;
> > +
> > +	kfence_dir = debugfs_create_dir("kfence", NULL);
> >   	debugfs_create_file("stats", 0444, kfence_dir, NULL, &stats_fops);
> >   	debugfs_create_file("objects", 0400, kfence_dir, NULL, &objects_fops);
> >   	return 0;
> > @@ -883,6 +887,8 @@ static int kfence_init_late(void)
> >   	}
> >   	kfence_init_enable();
> > +	kfence_debugfs_init();
> > +
> >   	return 0;
> >   }
> 
> I have implemented a following patch based on v5.15 branch.
> 
> From ba26f344fa3e477456a3cc60488a7b8e5af0e88d Mon Sep 17 00:00:00 2001
> From: Muchun Song <songmuchun@bytedance.com>
> Date: Wed, 15 Mar 2023 11:44:41 +0800
> Subject: [PATCH] mm: kfence: fix using kfence_metadata without
> initialization
>  in show_object()
> 
> The variable kfence_metadata is initialized in kfence_init_pool(), then,
> it is not initialized if kfence is disabled after booting.  In this case,
> kfence_metadata will be used (e.g.  ->lock and ->state fields) without
> initialization when reading /sys/kernel/debug/kfence/objects.  There will
> be a warning if you enable CONFIG_DEBUG_SPINLOCK.  Fix it by creating
> debugfs files when necessary.
> 
> Link:
> https://lkml.kernel.org/r/20230315034441.44321-1-songmuchun@bytedance.com
> Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> Tested-by: Marco Elver <elver@google.com>
> Reviewed-by: Marco Elver <elver@google.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Jann Horn <jannh@google.com>
> Cc: SeongJae Park <sjpark@amazon.de>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>  mm/kfence/core.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/kfence/core.c b/mm/kfence/core.c
> index 39a6c434e355..573f34e6af0b 100644
> --- a/mm/kfence/core.c
> +++ b/mm/kfence/core.c
> @@ -678,10 +678,14 @@ static const struct file_operations objects_fops = {
>      .release = seq_release,
>  };
> 

Patch is corrupted with the whitespace eaten by your email client.  Can
you resend this in a format that it can be applied?

thanks,

greg k-h