| Message ID | cover.1539702969.git.joseph.salisbury@canonical.com |
|---|---|
| Headers | show |
| Series | Fixes for LP:1792195 | expand |
On 2018-10-16 12:11:07 , Joseph Salisbury wrote: > == SRU Justification == > IBM is requesting these commits in bionic and cosmic. These commits > also rely on commit 7acf50e4efa6, which was SRU'd in bug 1792102. > > Description of bug: > GPFS mmfsd daemon is mapping shared tracing buffer(allocated from kernel > driver using vmalloc) and then writing trace records from user space threads > in parallel. While the SIGBUS happened, the access virtual memory address > is in the mapped range, no overflow on access. > > The root cause is that for PTEs created by a driver at mmap time (ie, that > aren't created dynamically at fault time), it's not legit for ptep_set_access_flags() > to make them invalid even temporarily. A concurrent access while they are > invalid will be unable to service the page fault and will cause as SIGBUS. > > > == Fixes == > bd0dbb73e013 ("powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid.") > f08d08f3db55 ("powerpc/mm/radix: Only need the Nest MMU workaround for R -> RW transition") > > == Regression Potential == > Low. Limited to powerpc. > > == Test Case == > A test kernel was built with these patches and tested by IBM. > IBM states the test kernel resolved the bug. > > Aneesh Kumar K.V (2): > powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid. > powerpc/mm/radix: Only need the Nest MMU workaround for R -> RW > transition > > arch/powerpc/include/asm/book3s/64/pgtable.h | 18 +++++++++++++++++- > arch/powerpc/mm/pgtable-radix.c | 8 +++++--- > 2 files changed, 22 insertions(+), 4 deletions(-) > Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
On 16.10.18 18:11, Joseph Salisbury wrote: > == SRU Justification == > IBM is requesting these commits in bionic and cosmic. These commits > also rely on commit 7acf50e4efa6, which was SRU'd in bug 1792102. > > Description of bug: > GPFS mmfsd daemon is mapping shared tracing buffer(allocated from kernel > driver using vmalloc) and then writing trace records from user space threads > in parallel. While the SIGBUS happened, the access virtual memory address > is in the mapped range, no overflow on access. > > The root cause is that for PTEs created by a driver at mmap time (ie, that > aren't created dynamically at fault time), it's not legit for ptep_set_access_flags() > to make them invalid even temporarily. A concurrent access while they are > invalid will be unable to service the page fault and will cause as SIGBUS. > > > == Fixes == > bd0dbb73e013 ("powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid.") > f08d08f3db55 ("powerpc/mm/radix: Only need the Nest MMU workaround for R -> RW transition") > > == Regression Potential == > Low. Limited to powerpc. > > == Test Case == > A test kernel was built with these patches and tested by IBM. > IBM states the test kernel resolved the bug. > > Aneesh Kumar K.V (2): > powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid. > powerpc/mm/radix: Only need the Nest MMU workaround for R -> RW > transition > > arch/powerpc/include/asm/book3s/64/pgtable.h | 18 +++++++++++++++++- > arch/powerpc/mm/pgtable-radix.c | 8 +++++--- > 2 files changed, 22 insertions(+), 4 deletions(-) > Acked-by: Stefan Bader <stefan.bader@canonical.com>
On 2018-10-16 12:11:07 , Joseph Salisbury wrote: > == SRU Justification == > IBM is requesting these commits in bionic and cosmic. These commits > also rely on commit 7acf50e4efa6, which was SRU'd in bug 1792102. > > Description of bug: > GPFS mmfsd daemon is mapping shared tracing buffer(allocated from kernel > driver using vmalloc) and then writing trace records from user space threads > in parallel. While the SIGBUS happened, the access virtual memory address > is in the mapped range, no overflow on access. > > The root cause is that for PTEs created by a driver at mmap time (ie, that > aren't created dynamically at fault time), it's not legit for ptep_set_access_flags() > to make them invalid even temporarily. A concurrent access while they are > invalid will be unable to service the page fault and will cause as SIGBUS. > > > == Fixes == > bd0dbb73e013 ("powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid.") > f08d08f3db55 ("powerpc/mm/radix: Only need the Nest MMU workaround for R -> RW transition") > > == Regression Potential == > Low. Limited to powerpc. > > == Test Case == > A test kernel was built with these patches and tested by IBM. > IBM states the test kernel resolved the bug. > > Aneesh Kumar K.V (2): > powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid. > powerpc/mm/radix: Only need the Nest MMU workaround for R -> RW > transition > > arch/powerpc/include/asm/book3s/64/pgtable.h | 18 +++++++++++++++++- > arch/powerpc/mm/pgtable-radix.c | 8 +++++--- > 2 files changed, 22 insertions(+), 4 deletions(-) > > -- > 2.7.4 > > > -- > kernel-team mailing list > kernel-team@lists.ubuntu.com > https://lists.ubuntu.com/mailman/listinfo/kernel-team
== SRU Justification == IBM is requesting these commits in bionic and cosmic. These commits also rely on commit 7acf50e4efa6, which was SRU'd in bug 1792102. Description of bug: GPFS mmfsd daemon is mapping shared tracing buffer(allocated from kernel driver using vmalloc) and then writing trace records from user space threads in parallel. While the SIGBUS happened, the access virtual memory address is in the mapped range, no overflow on access. The root cause is that for PTEs created by a driver at mmap time (ie, that aren't created dynamically at fault time), it's not legit for ptep_set_access_flags() to make them invalid even temporarily. A concurrent access while they are invalid will be unable to service the page fault and will cause as SIGBUS. == Fixes == bd0dbb73e013 ("powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid.") f08d08f3db55 ("powerpc/mm/radix: Only need the Nest MMU workaround for R -> RW transition") == Regression Potential == Low. Limited to powerpc. == Test Case == A test kernel was built with these patches and tested by IBM. IBM states the test kernel resolved the bug. Aneesh Kumar K.V (2): powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid. powerpc/mm/radix: Only need the Nest MMU workaround for R -> RW transition arch/powerpc/include/asm/book3s/64/pgtable.h | 18 +++++++++++++++++- arch/powerpc/mm/pgtable-radix.c | 8 +++++--- 2 files changed, 22 insertions(+), 4 deletions(-)