svn commit: r247116 - in head/sys: fs/nfs fs/nfsclient kern nfsclient sys tools

[Andrew Turner]

On Mon, 25 Feb 2013 15:00:41 -0600
Alan Cox <alc at rice.edu> wrote:

> 
> On Feb 25, 2013, at 4:36 AM, Andrew Turner wrote:
> 
> > On Mon, 25 Feb 2013 10:50:19 +0200
> > Konstantin Belousov <kostikbel at gmail.com> wrote:
> > 
> >> On Mon, Feb 25, 2013 at 08:13:13PM +1300, Andrew Turner wrote:
> >>> On Thu, 21 Feb 2013 19:02:50 +0000 (UTC)
> >>> John Baldwin <jhb at FreeBSD.org> wrote:
> >>> 
> >>>> Author: jhb
> >>>> Date: Thu Feb 21 19:02:50 2013
> >>>> New Revision: 247116
> >>>> URL: http://svnweb.freebsd.org/changeset/base/247116
> >>>> 
> >>>> Log:
> >>>>  Further refine the handling of stop signals in the NFS client.
> >>>> The changes in r246417 were incomplete as they did not add
> >>>> explicit calls to sigdeferstop() around all the places that
> >>>> previously passed SBDRY to _sleep().  In addition,
> >>>> nfs_getcacheblk() could trigger a write RPC from getblk()
> >>>> resulting in sigdeferstop() recursing. Rather than manually
> >>>> deferring stop signals in specific places, change the VFS_*() and
> >>>> VOP_*() methods to defer stop signals for filesystems which
> >>>> request this behavior via a new VFCF_SBDRY flag. Note that this
> >>>> has to be a VFC flag rather than a MNTK flag so that it works
> >>>> properly with VFS_MOUNT() when the mount is not yet fully
> >>>> constructed.  For now, only the NFS clients are set this new flag
> >>>> in VFS_SET(). A few other related changes:
> >>>>  - Add an assertion to ensure that TDF_SBDRY doesn't leak to
> >>>> userland.
> >>>>  - When a lookup request uses VOP_READLINK() to follow a symlink,
> >>>> mark the request as being on behalf of the thread performing the
> >>>> lookup (cnp_thread) rather than using a NULL thread pointer.
> >>>> This causes NFS to properly handle signals during this VOP on an
> >>>> interruptible mount.
> >>>> 
> >>>>  PR:		kern/176179
> >>>>  Reported by:	Russell Cattelan (sigdeferstop() recursion)
> >>>>  Reviewed by:	kib
> >>>>  MFC after:	1 month
> >>> 
> >>> This change is causing init to crash for me on armv6. I'm
> >>> netbooting a PandaBoard and it appears init is receiving a SIGABRT
> >>> before it gets into main().
> >>> 
> >>> Do you have any idea where I could look to track down why it is
> >>> doing this?
> >> 
> >> It is weird. SIGABRT sent by the kernel usually means that
> >> execve(2) already destroyed the previous address space of the
> >> process, but the new image cannot be activated, most likely due to
> >> image format error discovered too late, or resource shortage.
> >> 
> >> Could it be that some NFS RPC fails after the patch, but I cannot
> >> imagine why. You would need to track this. Also, verify that the
> >> init binary is correct.
> >> 
> >> I tried amd64 netboot, and it worked fine.
> > 
> > It looks like this change is not the issue, it just changed the
> > symptom enough for me to not realise I was seeing an issue where
> > it would crash the kernel before. I reinstated this change but only
> > allowed the kernel to access half the memory and it booted
> > correctly.
> > 
> > The real issue appears to be related to something in the vm layer
> > not working on ARM boards with too much memory (somewhere between
> > 512MiB and 1GiB).
> 
> 
> The recently introduced auto-sizing and cap may be too optimistic.
> In fact, they are greater than what we allow on 32-bit x86 and 32-bit
> MIPS.  Try the following.
> 
> Index: arm/include/vmparam.h
> ===================================================================
> --- arm/include/vmparam.h	(revision 247249)
> +++ arm/include/vmparam.h	(working copy)
> @@ -142,15 +142,15 @@
>  #define VM_KMEM_SIZE		(12*1024*1024)
>  #endif
>  #ifndef VM_KMEM_SIZE_SCALE
> -#define VM_KMEM_SIZE_SCALE	(2)
> +#define VM_KMEM_SIZE_SCALE	(3)
>  #endif
>  
>  /*
> - * Ceiling on the size of the kmem submap: 60% of the kernel map.
> + * Ceiling on the size of the kmem submap: 40% of the kernel map.
>   */
>  #ifndef VM_KMEM_SIZE_MAX
>  #define	VM_KMEM_SIZE_MAX	((vm_max_kernel_address - \
> -    VM_MIN_KERNEL_ADDRESS + 1) * 3 / 5)
> +    VM_MIN_KERNEL_ADDRESS + 1) * 2 / 5)
>  #endif
>  
>  #define MAXTSIZ 	(16*1024*1024)
> 
This patch fixes the boot for me. Is it likely we will see similar
issues with boards with more memory with this? I know of ARM boards
with 2GiB of ram, and I would expect to see some with more soon.

Andrew