When calling mprotect() with PROT_MTE, kernel will initialize MTE tags for every single page in the affected area. Soft lockup was observed when doing this for large HugeTLB memory area in our customer's workload (~300GB memory): watchdog: BUG: soft lockup - CPU#98 stuck for 23s! [t2_new_sysv:126916] CPU: 98 PID: 126916 Comm: t2_new_sysv Kdump: loaded Not tainted 6.17-rc7 Hardware name: GIGACOMPUTING R2A3-T40-AAV1/Jefferson CIO, BIOS 5.4.4.1 07/15/2025 pstate: 20400009 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : mte_clear_page_tags+0x14/0x24 lr : mte_sync_tags+0x1c0/0x240 sp : ffff80003150bb80 x29: ffff80003150bb80 x28: ffff00739e9705a8 x27: 0000ffd2d6a00000 x26: 0000ff8e4bc00000 x25: 00e80046cde00f45 x24: 0000000000022458 x23: 0000000000000000 x22: 0000000000000004 x21: 000000011b380000 x20: ffff000000000000 x19: 000000011b379f40 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : ffffc875e0aa5e2c x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000 x5 : fffffc01ce7a5c00 x4 : 00000000046cde00 x3 : fffffc0000000000 x2 : 0000000000000004 x1 : 0000000000000040 x0 : ffff0046cde7c000 Call trace:   mte_clear_page_tags+0x14/0x24   set_huge_pte_at+0x25c/0x280   hugetlb_change_protection+0x220/0x430   change_protection+0x5c/0x8c   mprotect_fixup+0x10c/0x294   do_mprotect_pkey.constprop.0+0x2e0/0x3d4   __arm64_sys_mprotect+0x24/0x44   invoke_syscall+0x50/0x160   el0_svc_common+0x48/0x144   do_el0_svc+0x30/0xe0   el0_svc+0x30/0xf0   el0t_64_sync_handler+0xc4/0x148   el0t_64_sync+0x1a4/0x1a8 Soft lockup is not triggered with THP or base page because there is cond_resched() called for each PMD size. So add cond_resched() for hugetlb to avoid soft lockup. Fixes: 25c17c4b55de ("hugetlb: arm64: add mte support") Tested-by: Carl Worth Signed-off-by: Yang Shi --- mm/hugetlb.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index cb5c4e79e0b8..fe6606d91b31 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -7242,6 +7242,8 @@ long hugetlb_change_protection(struct vm_area_struct *vma, psize); } spin_unlock(ptl); + + cond_resched(); } /* * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare -- 2.47.0