Marc Zyngier 2cbfdf4df5 iov_iter: Fix 9p virtio breakage
When switching to the new iovec accessors, a negation got subtly
dropped, leading to 9p being remarkably broken (here with kvmtool):

[    7.430941] VFS: Mounted root (9p filesystem) on device 0:15.
[    7.432080] devtmpfs: mounted
[    7.432717] Freeing unused kernel memory: 1344K
[    7.433658] Run /virt/init as init process
  Warning: unable to translate guest address 0x7e00902ff000 to host
  Warning: unable to translate guest address 0x7e00902fefc0 to host
  Warning: unable to translate guest address 0x7e00902ff000 to host
  Warning: unable to translate guest address 0x7e008febef80 to host
  Warning: unable to translate guest address 0x7e008febf000 to host
  Warning: unable to translate guest address 0x7e008febef00 to host
  Warning: unable to translate guest address 0x7e008febf000 to host
[    7.436376] Kernel panic - not syncing: Requested init /virt/init failed (error -8).
[    7.437554] CPU: 29 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc8-02267-g00e23707442a #291
[    7.439006] Hardware name: linux,dummy-virt (DT)
[    7.439902] Call trace:
[    7.440387]  dump_backtrace+0x0/0x148
[    7.441104]  show_stack+0x14/0x20
[    7.441768]  dump_stack+0x90/0xb4
[    7.442425]  panic+0x120/0x27c
[    7.443036]  kernel_init+0xa4/0x100
[    7.443725]  ret_from_fork+0x10/0x18
[    7.444444] SMP: stopping secondary CPUs
[    7.445391] Kernel Offset: disabled
[    7.446169] CPU features: 0x0,23000438
[    7.446974] Memory Limit: none
[    7.447645] ---[ end Kernel panic - not syncing: Requested init /virt/init failed (error -8). ]---

Restoring the missing "!" brings the guest back to life.

Fixes: 00e2370744 ("iov_iter: Use accessor function")
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-11-02 19:45:01 -04:00
2018-10-24 00:40:44 +01:00
2018-10-24 00:41:07 +01:00
2018-11-02 19:45:01 -04:00
2018-10-15 07:20:24 +02:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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