[024/212] mm, slub: validate slab from partial list or page allocator before making it cpu slab

Commit Message

Andrew Morton Sept. 2, 2021, 9:51 p.m. UTC

From: Vlastimil Babka <[e-mail]>
Subject: mm, slub: validate slab from partial list or page allocator before making it cpu slab

When we obtain a new slab page from node partial list or page allocator,
we assign it to kmem_cache_cpu, perform some checks, and if they fail, we
undo the assignment.

In order to allow doing the checks without irq disabled, restructure the
code so that the checks are done first, and kmem_cache_cpu.page assignment
only after they pass.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Vlastimil Babka <[e-mail]>
Cc: Christoph Lameter <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: Jann Horn <[e-mail]>
Cc: Jesper Dangaard Brouer <[e-mail]>
Cc: Joonsoo Kim <[e-mail]>
Cc: Mel Gorman <[e-mail]>
Cc: Mike Galbraith <[e-mail]>
Cc: Pekka Enberg <[e-mail]>
Cc: Sebastian Andrzej Siewior <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/slub.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

Patch

--- a/mm/slub.c~mm-slub-validate-slab-from-partial-list-or-page-allocator-before-making-it-cpu-slab
+++ a/mm/slub.c
@@ -2788,10 +2788,8 @@  new_objects:
 	lockdep_assert_irqs_disabled();
 
 	freelist = get_partial(s, gfpflags, node, &page);
-	if (freelist) {
-		c->page = page;
+	if (freelist)
 		goto check_new_page;
-	}
 
 	local_irq_restore(flags);
 	put_cpu_ptr(s->cpu_slab);
@@ -2804,9 +2802,6 @@  new_objects:
 	}
 
 	local_irq_save(flags);
-	if (c->page)
-		flush_slab(s, c);
-
 	/*
 	 * No other reference to the page yet so we can
 	 * muck around with it freely without cmpxchg
@@ -2815,14 +2810,12 @@  new_objects:
 	page->freelist = NULL;
 
 	stat(s, ALLOC_SLAB);
-	c->page = page;
 
 check_new_page:
 
 	if (kmem_cache_debug(s)) {
 		if (!alloc_debug_processing(s, page, freelist, addr)) {
 			/* Slab failed checks. Next slab needed */
-			c->page = NULL;
 			local_irq_restore(flags);
 			goto new_slab;
 		} else {
@@ -2841,10 +2834,18 @@  check_new_page:
 		 */
 		goto return_single;
 
+	if (unlikely(c->page))
+		flush_slab(s, c);
+	c->page = page;
+
 	goto load_freelist;
 
 return_single:
 
+	if (unlikely(c->page))
+		flush_slab(s, c);
+	c->page = page;
+
 	deactivate_slab(s, page, get_freepointer(s, freelist), c);
 	local_irq_restore(flags);
 	return freelist;