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: 9376130c390a ("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>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ef910bf..bef6cf2 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -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))
-                       break;
+                       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