The patch titled Subject: mm: handle COW faults under the VMA lock has been added to the -mm mm-unstable branch. Its filename is mm-handle-cow-faults-under-the-vma-lock.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-handle-cow-faults-under-the-vma-lock.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: mm: handle COW faults under the VMA lock Date: Fri, 6 Oct 2023 20:53:16 +0100 If the page is not currently present in the page tables, we need to call the page fault handler to find out which page we're supposed to COW, so we need to both check that there is already an anon_vma and that the fault handler doesn't need the mmap_lock. Link: https://lkml.kernel.org/r/20231006195318.4087158-5-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memory.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) --- a/mm/memory.c~mm-handle-cow-faults-under-the-vma-lock +++ a/mm/memory.c @@ -4642,13 +4642,11 @@ static vm_fault_t do_cow_fault(struct vm struct vm_area_struct *vma = vmf->vma; vm_fault_t ret; - if (vmf->flags & FAULT_FLAG_VMA_LOCK) { - vma_end_read(vma); - return VM_FAULT_RETRY; - } - - if (unlikely(anon_vma_prepare(vma))) - return VM_FAULT_OOM; + ret = vmf_can_call_fault(vmf); + if (!ret) + ret = vmf_anon_prepare(vmf); + if (ret) + return ret; vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address); if (!vmf->cow_page) _ Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are mm-make-lock_folio_maybe_drop_mmap-vma-lock-aware.patch mm-call-wp_page_copy-under-the-vma-lock.patch mm-handle-shared-faults-under-the-vma-lock.patch mm-handle-cow-faults-under-the-vma-lock.patch mm-handle-read-faults-under-the-vma-lock.patch mm-handle-write-faults-to-ro-pages-under-the-vma-lock.patch iomap-hold-state_lock-over-call-to-ifs_set_range_uptodate.patch iomap-protect-read_bytes_pending-with-the-state_lock.patch mm-add-folio_end_read.patch ext4-use-folio_end_read.patch buffer-use-folio_end_read.patch iomap-use-folio_end_read.patch bitops-add-xor_unlock_is_negative_byte.patch alpha-implement-xor_unlock_is_negative_byte.patch m68k-implement-xor_unlock_is_negative_byte.patch mips-implement-xor_unlock_is_negative_byte.patch powerpc-implement-arch_xor_unlock_is_negative_byte-on-32-bit.patch riscv-implement-xor_unlock_is_negative_byte.patch s390-implement-arch_xor_unlock_is_negative_byte.patch mm-delete-checks-for-xor_unlock_is_negative_byte.patch mm-add-folio_xor_flags_has_waiters.patch mm-make-__end_folio_writeback-return-void.patch mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback.patch