On 8/11/20 5:46 AM, Eugeniu Rosca wrote:
> Commit 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in
> deactivate_slab()") suffered an update when picked up from LKML [1].
>
> Specifically, relocating 'freelist = NULL' into 'freelist_corrupted()'
> created a no-op statement. Fix it by sticking to the behavior intended
> in the original patch [1]. Prefer the lowest-line-count solution.
>
> [1] https://lore.kernel.org/linux-mm/20200331031450.12182-1-dongli.zhang@xxxxxxxxxx/
>
> Fixes: 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in deactivate_slab()")
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
> ---
> mm/slub.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 68c02b2eecd9..9a3e963b02a3 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -677,7 +677,6 @@ static bool freelist_corrupted(struct kmem_cache *s, struct page *page,
> if ((s->flags & SLAB_CONSISTENCY_CHECKS) &&
> !check_valid_pointer(s, page, nextfree)) {
> object_err(s, page, freelist, "Freechain corrupt");
> - freelist = NULL;
> slab_fix(s, "Isolate corrupted freechain");
> return true;
> }
> @@ -2184,8 +2183,10 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page,
> * 'freelist' is already corrupted. So isolate all objects
> * starting at 'freelist'.
> */
> - if (freelist_corrupted(s, page, freelist, nextfree))
> + if (freelist_corrupted(s, page, freelist, nextfree)) {
> + freelist = NULL;
This is good to me.
However, this would confuse people when CONFIG_SLUB_DEBUG is not defined.
While reading the source code, people may be curious why to reset freelist when
CONFIG_SLUB_DEBUG is even not defined.
Dongli Zhang
