Skip to content
Snippets Groups Projects
user avatar
Juergen Gross authored
set_pmd_at() calls native_set_pmd() unconditionally on x86. This was
fine as long as only huge page entries were written via set_pmd_at(),
as Xen pv guests don't support those.

Commit 2c91bd4a ("mm: speed up mremap by 20x on large regions")
introduced a usage of set_pmd_at() possible on pv guests, leading to
failures like:

BUG: unable to handle kernel paging request at ffff888023e26778
#PF error: [PROT] [WRITE]
RIP: e030:move_page_tables+0x7c1/0xae0
move_vma.isra.3+0xd1/0x2d0
__se_sys_mremap+0x3c6/0x5b0
 do_syscall_64+0x49/0x100
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Make set_pmd_at() paravirt aware by just letting it use set_pmd().

Fixes: 2c91bd4a ("mm: speed up mremap by 20x on large regions")
Reported-by: default avatarSander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: xen-devel@lists.xenproject.org
Cc: boris.ostrovsky@oracle.com
Cc: sstabellini@kernel.org
Cc: hpa@zytor.com
Cc: bp@alien8.de
Cc: torvalds@linux-foundation.org
Link: https://lkml.kernel.org/r/20190210074056.11842-1-jgross@suse.com
20e55bc1
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.

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.