This comes from a report from Ives on using uffd-wp on shmem. More information can be found in patch 1 commit message. Patch 2 added some more sanity check when walking pgtables and when we convert the ptes into other forms e.g. for migration and swap. It will make the error trigger even earlier than the user could notice, meanwhile nail down the case if it's a wrong pgtable setup. Ives, I only attached the reported-by tag for you but not tested-by because the fix patch (patch 1) has a slight change compared to what I sent you before, but hopefully it should also work for you. If you want, feel free to reply directly here if the patch also works for you. We probably need patch 1 for stable (5.19+). Please have a look, thanks. Peter Xu (2): mm/migrate: Fix read-only page got writable when recover pte mm/uffd: Sanity check write bit for uffd-wp protected ptes arch/x86/include/asm/pgtable.h | 16 +++++++++++++++- mm/migrate.c | 8 +++++++- 2 files changed, 22 insertions(+), 2 deletions(-) -- 2.37.3
