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Re: [Qemu-devel] [PATCH 05/21] userfaultfd: add vm_userfaultfd_ctx to th
From: |
Pavel Emelyanov |
Subject: |
Re: [Qemu-devel] [PATCH 05/21] userfaultfd: add vm_userfaultfd_ctx to the vm_area_struct |
Date: |
Thu, 5 Mar 2015 20:48:22 +0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 |
> diff --git a/kernel/fork.c b/kernel/fork.c
> index cf65139..cb215c0 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -425,6 +425,7 @@ static int dup_mmap(struct mm_struct *mm, struct
> mm_struct *oldmm)
> goto fail_nomem_anon_vma_fork;
> tmp->vm_flags &= ~VM_LOCKED;
> tmp->vm_next = tmp->vm_prev = NULL;
> + tmp->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
This creates an interesting effect when the userfaultfd is used outside of
the process which created and activated one. If I try to monitor the memory
usage of one task with another, once the first task fork()-s, its child
begins to see zero-pages in the places where the monitor task was supposed
to insert pages with data.
> file = tmp->vm_file;
> if (file) {
> struct inode *inode = file_inode(file);
> .
>
- [Qemu-devel] [PATCH 19/21] userfaultfd: remap_pages: UFFDIO_REMAP preparation, (continued)
- [Qemu-devel] [PATCH 04/21] userfaultfd: linux/userfaultfd_k.h, Andrea Arcangeli, 2015/03/05
- [Qemu-devel] [PATCH 14/21] userfaultfd: mcopy_atomic|mfill_zeropage: UFFDIO_COPY|UFFDIO_ZEROPAGE preparation, Andrea Arcangeli, 2015/03/05
- [Qemu-devel] [PATCH 03/21] userfaultfd: uAPI, Andrea Arcangeli, 2015/03/05
- [Qemu-devel] [PATCH 05/21] userfaultfd: add vm_userfaultfd_ctx to the vm_area_struct, Andrea Arcangeli, 2015/03/05
- Re: [Qemu-devel] [PATCH 05/21] userfaultfd: add vm_userfaultfd_ctx to the vm_area_struct,
Pavel Emelyanov <=
- Re: [Qemu-devel] [PATCH 00/21] RFC: userfaultfd v3, Pavel Emelyanov, 2015/03/05
- [Qemu-devel] [PATCH 09/21] userfaultfd: prevent khugepaged to merge if userfaultfd is armed, Andrea Arcangeli, 2015/03/05
- [Qemu-devel] [PATCH 18/21] userfaultfd: UFFDIO_REMAP uABI, Andrea Arcangeli, 2015/03/05