Commit e9c3cda4 authored Mar 06, 2023 by Michal Hocko Committed by Andrew Morton Mar 23, 2023

mm, vmalloc: fix high order __GFP_NOFAIL allocations

Gao Xiang has reported that the page allocator complains about high order
__GFP_NOFAIL request coming from the vmalloc core:

 __alloc_pages+0x1cb/0x5b0 mm/page_alloc.c:5549
 alloc_pages+0x1aa/0x270 mm/mempolicy.c:2286
 vm_area_alloc_pages mm/vmalloc.c:2989 [inline]
 __vmalloc_area_node mm/vmalloc.c:3057 [inline]
 __vmalloc_node_range+0x978/0x13c0 mm/vmalloc.c:3227
 kvmalloc_node+0x156/0x1a0 mm/util.c:606
 kvmalloc include/linux/slab.h:737 [inline]
 kvmalloc_array include/linux/slab.h:755 [inline]
 kvcalloc include/linux/slab.h:760 [inline]

it seems that I have completely missed high order allocation backing
vmalloc areas case when implementing __GFP_NOFAIL support.  This means
that [k]vmalloc at al.  can allocate higher order allocations with
__GFP_NOFAIL which can trigger OOM killer for non-costly orders easily or
cause a lot of reclaim/compaction activity if those requests cannot be
satisfied.

Fix the issue by falling back to zero order allocations for __GFP_NOFAIL
requests if the high order request fails.

Link: https://lkml.kernel.org/r/ZAXynvdNqcI0f6Us@dhcp22.suse.cz


Fixes: 9376130c ("mm/vmalloc: add support for __GFP_NOFAIL")
Reported-by: Gao Xiang <hsiangkao@linux.alibaba.com>
  Link: https://lkml.kernel.org/r/20230305053035.1911-1-hsiangkao@linux.alibaba.com


Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Baoquan He <bhe@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent 1e760fa3

mm/vmalloc.c

+23 −5

Original line number	Diff line number	Diff line
		@@ -2883,6 +2883,8 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
		unsigned int order, unsigned int nr_pages, struct page **pages)
		{
		unsigned int nr_allocated = 0;
		gfp_t alloc_gfp = gfp;
		bool nofail = false;
		struct page *page;
		int i;

		@@ -2893,6 +2895,7 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
		* more permissive.
		*/
		if (!order) {
		/* bulk allocator doesn't support nofail req. officially */
		gfp_t bulk_gfp = gfp & ~__GFP_NOFAIL;

		while (nr_allocated < nr_pages) {
		@@ -2931,20 +2934,35 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
		if (nr != nr_pages_request)
		break;
		}
		} else if (gfp & __GFP_NOFAIL) {
		/*
		* Higher order nofail allocations are really expensive and
		* potentially dangerous (pre-mature OOM, disruptive reclaim
		* and compaction etc.
		*/
		alloc_gfp &= ~__GFP_NOFAIL;
		nofail = true;
		}

		/* High-order pages or fallback path if "bulk" fails. */

		while (nr_allocated < nr_pages) {
		if (fatal_signal_pending(current))
		break;

		if (nid == NUMA_NO_NODE)
		page = alloc_pages(gfp, order);
		page = alloc_pages(alloc_gfp, order);
		else
		page = alloc_pages_node(nid, gfp, order);
		if (unlikely(!page))
		page = alloc_pages_node(nid, alloc_gfp, order);
		if (unlikely(!page)) {
		if (!nofail)
		break;

		/* fall back to the zero order allocations */
		alloc_gfp \|= __GFP_NOFAIL;
		order = 0;
		continue;
		}

		/*
		* Higher order allocations must be able to be treated as
		* indepdenent small pages by callers (as they can with