Re: [PATCH] arm64/mm: Drop THP conditionality from FORCE_MAX_ZONEORDER

[Will Deacon]

On Mon, 1 Mar 2021 16:55:14 +0530, Anshuman Khandual wrote:
> Currently without THP being enabled, MAX_ORDER via FORCE_MAX_ZONEORDER gets
> reduced to 11, which falls below HUGETLB_PAGE_ORDER for certain 16K and 64K
> page size configurations. This is problematic which throws up the following
> warning during boot as pageblock_order via HUGETLB_PAGE_ORDER order exceeds
> MAX_ORDER.
> 
> WARNING: CPU: 7 PID: 127 at mm/vmstat.c:1092 __fragmentation_index+0x58/0x70
> Modules linked in:
> CPU: 7 PID: 127 Comm: kswapd0 Not tainted 5.12.0-rc1-00005-g0221e3101a1 #237
> Hardware name: linux,dummy-virt (DT)
> pstate: 20400005 (nzCv daif +PAN -UAO -TCO BTYPE=--)
> pc : __fragmentation_index+0x58/0x70
> lr : fragmentation_index+0x88/0xa8
> sp : ffff800016ccfc00
> x29: ffff800016ccfc00 x28: 0000000000000000
> x27: ffff800011fd4000 x26: 0000000000000002
> x25: ffff800016ccfda0 x24: 0000000000000002
> x23: 0000000000000640 x22: ffff0005ffcb5b18
> x21: 0000000000000002 x20: 000000000000000d
> x19: ffff0005ffcb3980 x18: 0000000000000004
> x17: 0000000000000001 x16: 0000000000000019
> x15: ffff800011ca7fb8 x14: 00000000000002b3
> x13: 0000000000000000 x12: 00000000000005e0
> x11: 0000000000000003 x10: 0000000000000080
> x9 : ffff800011c93948 x8 : 0000000000000000
> x7 : 0000000000000000 x6 : 0000000000007000
> x5 : 0000000000007944 x4 : 0000000000000032
> x3 : 000000000000001c x2 : 000000000000000b
> x1 : ffff800016ccfc10 x0 : 000000000000000d
> Call trace:
> __fragmentation_index+0x58/0x70
> compaction_suitable+0x58/0x78
> wakeup_kcompactd+0x8c/0xd8
> balance_pgdat+0x570/0x5d0
> kswapd+0x1e0/0x388
> kthread+0x154/0x158
> ret_from_fork+0x10/0x30
> 
> [...]

Applied to arm64 (for-next/fixes), thanks!

[1/1] arm64/mm: Drop THP conditionality from FORCE_MAX_ZONEORDER
      https://git.kernel.org/arm64/c/79cc2ed5a716

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev