https://github.com/torvalds/linux
Revision bce73e4842390f7b7309c8e253e139db71288ac3 authored by Christian Borntraeger on 13 July 2018, 23:58:52 UTC, committed by Linus Torvalds on 14 July 2018, 18:11:09 UTC
KVM guests on s390 can notify the host of unused pages. This can result in pte_unused callbacks to be true for KVM guest memory. If a page is unused (checked with pte_unused) we might drop this page instead of paging it. This can have side-effects on userfaultd, when the page in question was already migrated: The next access of that page will trigger a fault and a user fault instead of faulting in a new and empty zero page. As QEMU does not expect a userfault on an already migrated page this migration will fail. The most straightforward solution is to ignore the pte_unused hint if a userfault context is active for this VMA. Link: http://lkml.kernel.org/r/20180703171854.63981-1-borntraeger@de.ibm.com Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Janosch Frank <frankja@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Cornelia Huck <cohuck@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 3951dbf
Tip revision: bce73e4842390f7b7309c8e253e139db71288ac3 authored by Christian Borntraeger on 13 July 2018, 23:58:52 UTC
mm: do not drop unused pages when userfaultd is running
mm: do not drop unused pages when userfaultd is running
Tip revision: bce73e4
File | Mode | Size |
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Documentation | ||
LICENSES | ||
arch | ||
block | ||
certs | ||
crypto | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | -rw-r--r-- | 12.8 KB |
.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 31 bytes |
.gitattributes | -rw-r--r-- | 30 bytes |
.gitignore | -rw-r--r-- | 1.5 KB |
.mailmap | -rw-r--r-- | 9.3 KB |
COPYING | -rw-r--r-- | 423 bytes |
CREDITS | -rw-r--r-- | 96.3 KB |
Kbuild | -rw-r--r-- | 2.2 KB |
Kconfig | -rw-r--r-- | 321 bytes |
MAINTAINERS | -rw-r--r-- | 449.4 KB |
Makefile | -rw-r--r-- | 58.2 KB |
README | -rw-r--r-- | 800 bytes |
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