On Wed, 30 May 2012, Ian Campbell wrote: > On Thu, 2012-05-24 at 11:57 +0000, George Dunlap wrote: > > Package: linux-2.6 > > Version: 2.6.32-45 > > Severity: normal > > > > The kernel version in this package does not handle AIO to pages > > owned by guest domains ("foreign domains") properly. Newer versions of qemu > > will attempt to use AIO for disk reads and writes; this causes domain 0 to > > crash > > if you're running. > > Thanks George. Do you happen to have a log of the actual kernel crash? > > I think Stefano (CCd) has been fixing this issue (or at least one which > sounds very similar) in the upstream kernels recently. Stefano is there > anything specific I can backport to a Jeremy xen.git 2.6.32 style pvops > kernel? Or is there another appropriate fix? > > FYI Squeeze's kernel is based on e73f4955a821 from Jeremy's tree, > although with a bunch of fixes backported too.
We need to backport the m2p_override, this is a list of the relevant upstream commits: 289b777eac19c811b474593b4d2fd14e46340c23 b5eafe924bb054d7c56e6ebd18106352e8a3f916 448f2831934381e9d3c4d93e700ba7bbe14612dc 9b705f0e98c489b18ba22a6eab9d694b546c8552 87f1d40a706bdebdc8f959b9ac291d0d8fdfcc7e e1b478e4ec4477520767d1a920433626263a2a6b b254244d2682fe975630f176c25a4444cc4e088d cf8d91633ddef9e816ccbf3da833c79ce508988d 0f4b49eaf25e661fbe63a5370b7781166b34d616 0930bba674e248b921ea659b036ff02564e5a5f4 dc4972a4e2f3fee1663bd0670dfc4cd798d5f9b2 The backport is non-trivial, but I can help. As an alternative we could add a simple check to spot an attempt to use AIO on a granted page and return an error (still better than crashing): --- diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index a33e443..f060770 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -573,6 +573,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) vma->vm_flags |= VM_RESERVED; vma->vm_flags |= VM_DONTCOPY; vma->vm_flags |= VM_DONTEXPAND; + vma->vm_flags |= VM_FOREIGN; vma->vm_private_data = map; map->vma = vma; diff --git a/fs/aio.c b/fs/aio.c index 02a2c93..70b8854 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1655,6 +1655,8 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, for (i=0; i<nr; i++) { struct iocb __user *user_iocb; struct iocb tmp; + struct vm_area_struct *vma = NULL; + struct iovec *v = NULL; if (unlikely(__get_user(user_iocb, iocbpp + i))) { ret = -EFAULT; @@ -1666,6 +1668,19 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, break; } + down_read(¤t->mm->mmap_sem); + v = (struct iovec *) tmp.aio_buf; + /* just checking the first iovec is enough for now */ + if (v != NULL) + vma = find_vma(current->mm, (unsigned long) v->iov_base); + if (vma != NULL && vma->vm_flags & (VM_FOREIGN|VM_DONTEXPAND)) { + WARN_ONCE(1, "missing AIO support on granted pages\n"); + ret = -EFAULT; + up_read(¤t->mm->mmap_sem); + break; + } + up_read(¤t->mm->mmap_sem); + ret = io_submit_one(ctx, user_iocb, &tmp); if (ret) break; -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/alpine.DEB.2.00.1205311104510.26786@kaball-desktop