Re: [PATCH v3 23/40] mm/mlock: clear VMA_LOCKED_MASK over mmap callback
flat view
From: "Zi Yan" <ziy@nvidia.com>
Date: 2026-10-01 15:20:40
Also in:
bpf, fuse-devel, kvm, kvm-riscv, kvmarm, linux-arch, linux-doc, linux-fsdevel, linux-mm, linux-perf-users, linux-rdma, linux-riscv, linux-s390, linux-scsi, linux-sound, linux-trace-kernel, linux-usb, linuxppc-dev, lkml, selinux, sparclinux
On Thu Sep 17, 2026 at 12:22 PM EDT, Lorenzo Stoakes (ARM) wrote:
Currently there's a confusing mess around VMA_LOCKED_BIT and VMA_LOCKONFAULT_BIT. It is permitted for drivers to set any flags they like, with the VMA already possessing lock flags. This results in the absurd situation of a VMA possessing both VMA_SPECIAL_FLAGS and VMA_LOCKED_MASK flags, which is not permitted. This has resulted in mlock_vma_folio() having a very silly check for this scenario to work around it. There is no need for this - just clear the flags before invoking the hook and reinstate them afterwards if they are required. Nothing relies upon this being set during the mmap operation. mmap_prepare is unaffected by this so requires no fix. Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org> --- mm/internal.h | 9 +-------- mm/vma.c | 14 ++++++++++++++ 2 files changed, 15 insertions(+), 8 deletions(-)
<snip>
quoted hunk ↗ jump to hunk
+ /* If VMA flags still valid for locked mask, reinstate. */ + if (vma_supports_mlock(vma)) { + const vma_flags_t mask = + vma_flags_and_mask(&map->vma_flags, + VMA_LOCKED_MASK); + + vma_set_flags_mask(vma, mask);
It took me a while to figure out vma_set_flags_mask() is an OR operation.
quoted hunk ↗ jump to hunk
+ } + map->vma_flags = vma->flags; return 0;
Otherwise, LGTM. Reviewed-by: Zi Yan <ziy@nvidia.com> -- Best Regards, Yan, Zi