| Message ID | 1425575884-2574-6-git-send-email-aarcange@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> 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); > . > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 199a03a..fbf21f5 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -247,6 +247,16 @@ struct vm_region { * this region */ }; +#ifdef CONFIG_USERFAULTFD +#define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) { NULL, }) +struct vm_userfaultfd_ctx { + struct userfaultfd_ctx *ctx; +}; +#else /* CONFIG_USERFAULTFD */ +#define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) {}) +struct vm_userfaultfd_ctx {}; +#endif /* CONFIG_USERFAULTFD */ + /* * This struct defines a memory VMM memory area. There is one of these * per VM-area/task. A VM area is any part of the process virtual memory @@ -313,6 +323,7 @@ struct vm_area_struct { #ifdef CONFIG_NUMA struct mempolicy *vm_policy; /* NUMA policy for the VMA */ #endif + struct vm_userfaultfd_ctx vm_userfaultfd_ctx; }; struct core_thread { 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; file = tmp->vm_file; if (file) { struct inode *inode = file_inode(file);
This adds the vm_userfaultfd_ctx to the vm_area_struct. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> --- include/linux/mm_types.h | 11 +++++++++++ kernel/fork.c | 1 + 2 files changed, 12 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html