The patch titled
Subject: mm, slub: call deactivate_slab() without disabling irqs
has been removed from the -mm tree. Its filename was
mm-slub-call-deactivate_slab-without-disabling-irqs.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm, slub: call deactivate_slab() without disabling irqs
The function is now safe to be called with irqs enabled, so move the calls
outside of irq disabled sections.
When called from ___slab_alloc() -> flush_slab() we have irqs disabled, so
to reenable them before deactivate_slab() we need to open-code
flush_slab() in ___slab_alloc() and reenable irqs after modifying the
kmem_cache_cpu fields. But that means a IRQ handler meanwhile might have
assigned a new page to kmem_cache_cpu.page so we have to retry the whole
check.
The remaining callers of flush_slab() are the IPI handler which has
disabled irqs anyway, and slub_cpu_dead() which will be dealt with in the
following patch.
Link: https://lkml.kernel.org/r/20210904105003.11688-21-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Qian Cai <quic_qiancai@xxxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
--- a/mm/slub.c~mm-slub-call-deactivate_slab-without-disabling-irqs
+++ a/mm/slub.c
@@ -2779,8 +2779,8 @@ deactivate_slab:
freelist = c->freelist;
c->page = NULL;
c->freelist = NULL;
- deactivate_slab(s, page, freelist);
local_irq_restore(flags);
+ deactivate_slab(s, page, freelist);
new_slab:
@@ -2848,18 +2848,32 @@ check_new_page:
*/
goto return_single;
+retry_load_page:
+
local_irq_save(flags);
- if (unlikely(c->page))
- flush_slab(s, c);
+ if (unlikely(c->page)) {
+ void *flush_freelist = c->freelist;
+ struct page *flush_page = c->page;
+
+ c->page = NULL;
+ c->freelist = NULL;
+ c->tid = next_tid(c->tid);
+
+ local_irq_restore(flags);
+
+ deactivate_slab(s, flush_page, flush_freelist);
+
+ stat(s, CPUSLAB_FLUSH);
+
+ goto retry_load_page;
+ }
c->page = page;
goto load_freelist;
return_single:
- local_irq_save(flags);
deactivate_slab(s, page, get_freepointer(s, freelist));
- local_irq_restore(flags);
return freelist;
}
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
