From 343ab8178f318b6006d54865972ff9c433b29e10 Mon Sep 17 00:00:00 2001 From: "Uladzislau Rezki (Sony)" Date: Thu, 2 Sep 2021 14:57:16 -0700 Subject: mm/vmalloc: use batched page requests in bulk-allocator In case of simultaneous vmalloc allocations, for example it is 1GB and 12 CPUs my system is able to hit "BUG: soft lockup" for !CONFIG_PREEMPT kernel. RIP: 0010:__alloc_pages_bulk+0xa9f/0xbb0 Call Trace: __vmalloc_node_range+0x11c/0x2d0 __vmalloc_node+0x4b/0x70 fix_size_alloc_test+0x44/0x60 [test_vmalloc] test_func+0xe7/0x1f0 [test_vmalloc] kthread+0x11a/0x140 ret_from_fork+0x22/0x30 To address this issue invoke a bulk-allocator many times until all pages are obtained, i.e. do batched page requests adding cond_resched() meanwhile to reschedule. Batched value is hard-coded and is 100 pages per call. Link: https://lkml.kernel.org/r/20210707182639.31282-1-urezki@gmail.com Signed-off-by: Uladzislau Rezki (Sony) Acked-by: Michal Hocko Cc: Christoph Hellwig Cc: Hillf Danton Cc: Matthew Wilcox Cc: Mel Gorman Cc: Nicholas Piggin Cc: Oleksiy Avramchenko Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmalloc.c | 32 +++++++++++++++++++++++++++----- 1 file changed, 27 insertions(+), 5 deletions(-) (limited to 'mm/vmalloc.c') diff --git a/mm/vmalloc.c b/mm/vmalloc.c index d5cd52805149..24bc65f02d04 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2779,7 +2779,7 @@ EXPORT_SYMBOL_GPL(vmap_pfn); static inline unsigned int vm_area_alloc_pages(gfp_t gfp, int nid, - unsigned int order, unsigned long nr_pages, struct page **pages) + unsigned int order, unsigned int nr_pages, struct page **pages) { unsigned int nr_allocated = 0; @@ -2789,10 +2789,32 @@ vm_area_alloc_pages(gfp_t gfp, int nid, * to fails, fallback to a single page allocator that is * more permissive. */ - if (!order) - nr_allocated = alloc_pages_bulk_array_node( - gfp, nid, nr_pages, pages); - else + if (!order) { + while (nr_allocated < nr_pages) { + unsigned int nr, nr_pages_request; + + /* + * A maximum allowed request is hard-coded and is 100 + * pages per call. That is done in order to prevent a + * long preemption off scenario in the bulk-allocator + * so the range is [1:100]. + */ + nr_pages_request = min(100U, nr_pages - nr_allocated); + + nr = alloc_pages_bulk_array_node(gfp, nid, + nr_pages_request, pages + nr_allocated); + + nr_allocated += nr; + cond_resched(); + + /* + * If zero or pages were obtained partly, + * fallback to a single page allocator. + */ + if (nr != nr_pages_request) + break; + } + } else /* * Compound pages required for remap_vmalloc_page if * high-order pages. -- cgit