With HUGETLB_PAGE_SIZE_VARIABLE enabled, pageblock_order cannot be assigned as HUGETLB_PAGE_ORDER when it is greater than or equal to MAX_ORDER during set_pageblock_order(). Otherwise the following warning is triggered during boot as detected on an arm64 platform. WARNING: CPU: 5 PID: 124 at mm/vmstat.c:1080 __fragmentation_index+0xa4/0xc0 Modules linked in: CPU: 5 PID: 124 Comm: kswapd0 Not tainted 5.11.0-rc6-00004-ga0ea7d62002 #159 Hardware name: linux,dummy-virt (DT) [ 8.810673] pstate: 20400005 (nzCv daif +PAN -UAO -TCO BTYPE=--) [ 8.811732] pc : __fragmentation_index+0xa4/0xc0 [ 8.812555] lr : fragmentation_index+0xf8/0x138 [ 8.813360] sp : ffff0000864079b0 [ 8.813958] x29: ffff0000864079b0 x28: 0000000000000372 [ 8.814901] x27: 0000000000007682 x26: ffff8000135b3948 [ 8.815847] x25: 1fffe00010c80f48 x24: 0000000000000000 [ 8.816805] x23: 0000000000000000 x22: 000000000000000d [ 8.817764] x21: 0000000000000030 x20: ffff0005ffcb4d58 [ 8.818712] x19: 000000000000000b x18: 0000000000000000 [ 8.819656] x17: 0000000000000000 x16: 0000000000000000 [ 8.820613] x15: 0000000000000000 x14: ffff8000114c6258 [ 8.821560] x13: ffff6000bff969ba x12: 1fffe000bff969b9 [ 8.822514] x11: 1fffe000bff969b9 x10: ffff6000bff969b9 [ 8.823461] x9 : dfff800000000000 x8 : ffff0005ffcb4dcf [ 8.824415] x7 : 0000000000000001 x6 : 0000000041b58ab3 [ 8.825359] x5 : ffff600010c80f48 x4 : dfff800000000000 [ 8.826313] x3 : ffff8000102be670 x2 : 0000000000000007 [ 8.827259] x1 : ffff000086407a60 x0 : 000000000000000d [ 8.828218] Call trace: [ 8.828667] __fragmentation_index+0xa4/0xc0 [ 8.829436] fragmentation_index+0xf8/0x138 [ 8.830194] compaction_suitable+0x98/0xb8 [ 8.830934] wakeup_kcompactd+0xdc/0x128 [ 8.831640] balance_pgdat+0x71c/0x7a0 [ 8.832327] kswapd+0x31c/0x520 [ 8.832902] kthread+0x224/0x230 [ 8.833491] ret_from_fork+0x10/0x30 [ 8.834150] ---[ end trace 472836f79c15516b ]--- The above warning happens because pageblock_order exceeds MAX_ORDER, caused by large HUGETLB_PAGE_ORDER on certain platforms like arm64. Lets prevent the scenario by first checking HUGETLB_PAGE_ORDER against MAX_ORDER, before its assignment as pageblock_order. Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: linux-mm@xxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 519a60d5b6f7..36473f2fa683 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6798,7 +6798,7 @@ void __init set_pageblock_order(void) if (pageblock_order) return; - if (HPAGE_SHIFT > PAGE_SHIFT) + if ((HPAGE_SHIFT > PAGE_SHIFT) && (HUGETLB_PAGE_ORDER < MAX_ORDER)) order = HUGETLB_PAGE_ORDER; else order = MAX_ORDER - 1; -- 2.20.1
