On Tue, 11 Aug 2020 14:46:56 +0200 Eugeniu Rosca erosca@de.adit-jv.com 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@oracle....
...
--- 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;@@ -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; break;}do { prior = page->freelist;
Looks right.
What are the runtime effects of this change? In other words, what are the end user visible effects of the present defect?