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charset=us-ascii Content-Disposition: inline In-Reply-To: <20250512150333.5589-1-ryan.roberts@arm.com> X-Rspamd-Queue-Id: 378A640004 X-Stat-Signature: ygn3ab4y5a6fj9qfayae4bjfp18ychgk X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1747076132-663985 X-HE-Meta: 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 dRNSqiEZ 9xkUOfi06myfV32exlF8BX8RaD1nvsoMBWYocFYorJ+6DKBP5aWoDMcYd4H6kLCgIw4sqyxdDBJbmryRLtIN67t/kS+gc3SmWTj3skpPvNsOlA3XuTQ6tV+eO3g== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, May 12, 2025 at 04:03:31PM +0100, Ryan Roberts wrote: > lazy_mmu_mode is not supposed to permit nesting. But in practice this > does happen with CONFIG_DEBUG_PAGEALLOC, where a page allocation inside > a lazy_mmu_mode section (such as zap_pte_range()) will change > permissions on the linear map with apply_to_page_range(), which > re-enters lazy_mmu_mode (see stack trace below). > > The warning checking that nesting was not happening was previously being > triggered due to this. So let's relax by removing the warning and > tolerate nesting in the arm64 implementation. The first (inner) call to > arch_leave_lazy_mmu_mode() will flush and clear the flag such that the > remainder of the work in the outer nest behaves as if outside of lazy > mmu mode. This is safe and keeps tracking simple. > > Code review suggests powerpc deals with this issue in the same way. > > ------------[ cut here ]------------ > WARNING: CPU: 6 PID: 1 at arch/arm64/include/asm/pgtable.h:89 __apply_to_page_range+0x85c/0x9f8 > Modules linked in: ip_tables x_tables ipv6 > CPU: 6 UID: 0 PID: 1 Comm: systemd Not tainted 6.15.0-rc5-00075-g676795fe9cf6 #1 PREEMPT > Hardware name: QEMU KVM Virtual Machine, BIOS 2024.08-4 10/25/2024 > pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : __apply_to_page_range+0x85c/0x9f8 > lr : __apply_to_page_range+0x2b4/0x9f8 > sp : ffff80008009b3c0 > x29: ffff80008009b460 x28: ffff0000c43a3000 x27: ffff0001ff62b108 > x26: ffff0000c43a4000 x25: 0000000000000001 x24: 0010000000000001 > x23: ffffbf24c9c209c0 x22: ffff80008009b4d0 x21: ffffbf24c74a3b20 > x20: ffff0000c43a3000 x19: ffff0001ff609d18 x18: 0000000000000001 > x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000003 > x14: 0000000000000028 x13: ffffbf24c97c1000 x12: ffff0000c43a3fff > x11: ffffbf24cacc9a70 x10: ffff0000c43a3fff x9 : ffff0001fffff018 > x8 : 0000000000000012 x7 : ffff0000c43a4000 x6 : ffff0000c43a4000 > x5 : ffffbf24c9c209c0 x4 : ffff0000c43a3fff x3 : ffff0001ff609000 > x2 : 0000000000000d18 x1 : ffff0000c03e8000 x0 : 0000000080000000 > Call trace: > __apply_to_page_range+0x85c/0x9f8 (P) > apply_to_page_range+0x14/0x20 > set_memory_valid+0x5c/0xd8 > __kernel_map_pages+0x84/0xc0 > get_page_from_freelist+0x1110/0x1340 > __alloc_frozen_pages_noprof+0x114/0x1178 > alloc_pages_mpol+0xb8/0x1d0 > alloc_frozen_pages_noprof+0x48/0xc0 > alloc_pages_noprof+0x10/0x60 > get_free_pages_noprof+0x14/0x90 > __tlb_remove_folio_pages_size.isra.0+0xe4/0x140 > __tlb_remove_folio_pages+0x10/0x20 > unmap_page_range+0xa1c/0x14c0 > unmap_single_vma.isra.0+0x48/0x90 > unmap_vmas+0xe0/0x200 > vms_clear_ptes+0xf4/0x140 > vms_complete_munmap_vmas+0x7c/0x208 > do_vmi_align_munmap+0x180/0x1a8 > do_vmi_munmap+0xac/0x188 > __vm_munmap+0xe0/0x1e0 > __arm64_sys_munmap+0x20/0x38 > invoke_syscall+0x48/0x104 > el0_svc_common.constprop.0+0x40/0xe0 > do_el0_svc+0x1c/0x28 > el0_svc+0x4c/0x16c > el0t_64_sync_handler+0x10c/0x140 > el0t_64_sync+0x198/0x19c > irq event stamp: 281312 > hardirqs last enabled at (281311): [] bad_range+0x164/0x1c0 > hardirqs last disabled at (281312): [] el1_dbg+0x24/0x98 > softirqs last enabled at (281054): [] handle_softirqs+0x4cc/0x518 > softirqs last disabled at (281019): [] __do_softirq+0x14/0x20 > ---[ end trace 0000000000000000 ]--- > > Fixes: 5fdd05efa1cd ("arm64/mm: Batch barriers when updating kernel mappings") > Reported-by: Catalin Marinas > Closes: https://lore.kernel.org/linux-arm-kernel/aCH0TLRQslXHin5Q@arm.com/ > Signed-off-by: Ryan Roberts Thanks. This works, no more warnings. The comment looks fine. Reviewed-by: Catalin Marinas