From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm, slub: restore irqs around calling new_slab() allocate_slab() currently re-enables irqs before calling to the page allocator. It depends on gfpflags_allow_blocking() to determine if it's safe to do so. Now we can instead simply restore irq before calling it through new_slab(). The other caller early_kmem_cache_node_alloc() is unaffected by this. Link: https://lkml.kernel.org/r/20210904105003.11688-15-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 | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --- a/mm/slub.c~mm-slub-restore-irqs-around-calling-new_slab +++ a/mm/slub.c @@ -1809,9 +1809,6 @@ static struct page *allocate_slab(struct flags &= gfp_allowed_mask; - if (gfpflags_allow_blocking(flags)) - local_irq_enable(); - flags |= s->allocflags; /* @@ -1870,8 +1867,6 @@ static struct page *allocate_slab(struct page->frozen = 1; out: - if (gfpflags_allow_blocking(flags)) - local_irq_disable(); if (!page) return NULL; @@ -2812,16 +2807,17 @@ new_objects: goto check_new_page; } + local_irq_restore(flags); put_cpu_ptr(s->cpu_slab); page = new_slab(s, gfpflags, node); c = get_cpu_ptr(s->cpu_slab); if (unlikely(!page)) { - local_irq_restore(flags); slab_out_of_memory(s, gfpflags, node); return NULL; } + local_irq_save(flags); if (c->page) flush_slab(s, c); _
