@@ -35,6 +35,7 @@
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/highmem.h>
+#include <linux/mempolicy.h>
#include <xen/xen.h>
#include <xen/grant_table.h>
@@ -433,10 +434,28 @@ static void gntdev_vma_close(struct vm_area_struct *vma)
return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT];
}
+#ifdef CONFIG_NUMA
+/*
+ * We have this op to make sure callers (such as vma_policy_mof()) don't
+ * check current task's policy which may include migrate flags (MPOL_F_MOF
+ * or MPOL_F_MORON)
+ */
+static struct mempolicy *gntdev_vma_get_policy(struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ if (mpol_needs_cond_ref(vma->vm_policy))
+ mpol_get(vma->vm_policy);
+ return vma->vm_policy;
+}
+#endif
+
static const struct vm_operations_struct gntdev_vmops = {
.open = gntdev_vma_open,
.close = gntdev_vma_close,
.find_special_page = gntdev_vma_find_special_page,
+#ifdef CONFIG_NUMA
+ .get_policy = gntdev_vma_get_policy,
+#endif
};
/* ------------------------------------------------------------------ */
@@ -1007,7 +1026,13 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
vma->vm_ops = &gntdev_vmops;
- vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_IO;
+ vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+
+#ifdef CONFIG_NUMA
+ /* Prevent NUMA balancing */
+ if (vma->vm_policy)
+ vma->vm_policy->flags &= ~(MPOL_F_MOF | MPOL_F_MORON);
+#endif
if (use_ptemod)
vma->vm_flags |= VM_DONTCOPY;
Commit 9c17d96500f7 ("xen/gntdev: Grant maps should not be subject to NUMA balancing") set VM_IO flag to prevent grant maps from being subjected to NUMA balancing. It was discovered recently that this flag causes get_user_pages() to always fail with -EFAULT. check_vma_flags __get_user_pages __get_user_pages_locked __get_user_pages_unlocked get_user_pages_fast iov_iter_get_pages dio_refill_pages do_direct_IO do_blockdev_direct_IO do_blockdev_direct_IO ext4_direct_IO_read generic_file_read_iter aio_run_iocb (which can happen if guest's vdisk has direct-io-safe option). To avoid this don't use vm_flags. Instead, use mempolicy that prohibits page migration (i.e. clear MPOL_F_MOF|MPOL_F_MORON) and make sure we don't consult task's policy (which may include those flags) if vma doesn't have one. Reported-by: Olaf Hering <olaf@aepfle.de> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: stable@vger.kernel.org --- Changes in v3: * Don't use __mpol_dup() and get_task_policy() which are not exported for use by drivers. Add vm_operations_struct.get_policy(). * Copy to stable drivers/xen/gntdev.c | 27 ++++++++++++++++++++++++++- 1 files changed, 26 insertions(+), 1 deletions(-)