linux-stable.git/fs/proc/task_mmu.c, branch linux-5.2.y

proc: use down_read_killable mmap_sem for /proc/pid/maps

2019-07-31T05:24:55+00:00

[ Upstream commit 8a713e7df3352b8d9392476e9cf29e4e185dac32 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

This function is also used for /proc/pid/smaps.

Link: http://lkml.kernel.org/r/156007493160.3335.14447544314127417266.stgit@buzz
Signed-off-by: Konstantin Khlebnikov 
Reviewed-by: Roman Gushchin 
Reviewed-by: Cyrill Gorcunov 
Reviewed-by: Kirill Tkhai 
Acked-by: Michal Hocko 
Cc: Alexey Dobriyan 
Cc: Al Viro 
Cc: Matthew Wilcox 
Cc: Michal Koutný 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

proc: use down_read_killable mmap_sem for /proc/pid/clear_refs

2019-07-31T05:24:54+00:00

[ Upstream commit c46038017fbdcac627b670c9d4176f1d0c2f5fa3 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

Replace the only unkillable mmap_sem lock in clear_refs_write().

Link: http://lkml.kernel.org/r/156007493826.3335.5424884725467456239.stgit@buzz
Signed-off-by: Konstantin Khlebnikov 
Reviewed-by: Roman Gushchin 
Reviewed-by: Cyrill Gorcunov 
Reviewed-by: Kirill Tkhai 
Acked-by: Michal Hocko 
Cc: Alexey Dobriyan 
Cc: Al Viro 
Cc: Matthew Wilcox 
Cc: Michal Koutný 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

proc: use down_read_killable mmap_sem for /proc/pid/pagemap

2019-07-31T05:24:54+00:00

[ Upstream commit ad80b932c57d85fd6377f97f359b025baf179a87 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

Link: http://lkml.kernel.org/r/156007493638.3335.4872164955523928492.stgit@buzz
Signed-off-by: Konstantin Khlebnikov 
Reviewed-by: Roman Gushchin 
Reviewed-by: Cyrill Gorcunov 
Reviewed-by: Kirill Tkhai 
Acked-by: Michal Hocko 
Cc: Alexey Dobriyan 
Cc: Al Viro 
Cc: Matthew Wilcox 
Cc: Michal Koutný 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

proc: use down_read_killable mmap_sem for /proc/pid/smaps_rollup

2019-07-31T05:24:54+00:00

[ Upstream commit a26a97815548574213fd37f29b4b78ccc6d9ed20 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

Link: http://lkml.kernel.org/r/156007493429.3335.14666825072272692455.stgit@buzz
Signed-off-by: Konstantin Khlebnikov 
Reviewed-by: Roman Gushchin 
Reviewed-by: Cyrill Gorcunov 
Reviewed-by: Kirill Tkhai 
Acked-by: Michal Hocko 
Cc: Alexey Dobriyan 
Cc: Al Viro 
Cc: Matthew Wilcox 
Cc: Michal Koutný 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm/mmu_notifier: use correct mmu_notifier events for each invalidation

2019-05-14T16:47:49+00:00

This updates each existing invalidation to use the correct mmu notifier
event that represent what is happening to the CPU page table.  See the
patch which introduced the events to see the rational behind this.

Link: http://lkml.kernel.org/r/20190326164747.24405-7-jglisse@redhat.com
Signed-off-by: Jérôme Glisse 
Reviewed-by: Ralph Campbell 
Reviewed-by: Ira Weiny 
Cc: Christian König 
Cc: Joonas Lahtinen 
Cc: Jani Nikula 
Cc: Rodrigo Vivi 
Cc: Jan Kara 
Cc: Andrea Arcangeli 
Cc: Peter Xu 
Cc: Felix Kuehling 
Cc: Jason Gunthorpe 
Cc: Ross Zwisler 
Cc: Dan Williams 
Cc: Paolo Bonzini 
Cc: Radim Krcmar 
Cc: Michal Hocko 
Cc: Christian Koenig 
Cc: John Hubbard 
Cc: Arnd Bergmann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/mmu_notifier: contextual information for event triggering invalidation

2019-05-14T16:47:49+00:00

CPU page table update can happens for many reasons, not only as a result
of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also as
a result of kernel activities (memory compression, reclaim, migration,
...).

Users of mmu notifier API track changes to the CPU page table and take
specific action for them.  While current API only provide range of virtual
address affected by the change, not why the changes is happening.

This patchset do the initial mechanical convertion of all the places that
calls mmu_notifier_range_init to also provide the default MMU_NOTIFY_UNMAP
event as well as the vma if it is know (most invalidation happens against
a given vma).  Passing down the vma allows the users of mmu notifier to
inspect the new vma page protection.

The MMU_NOTIFY_UNMAP is always the safe default as users of mmu notifier
should assume that every for the range is going away when that event
happens.  A latter patch do convert mm call path to use a more appropriate
events for each call.

This is done as 2 patches so that no call site is forgotten especialy
as it uses this following coccinelle patch:

%<----------------------------------------------------------------------
@@
identifier I1, I2, I3, I4;
@@
static inline void mmu_notifier_range_init(struct mmu_notifier_range *I1,
+enum mmu_notifier_event event,
+unsigned flags,
+struct vm_area_struct *vma,
struct mm_struct *I2, unsigned long I3, unsigned long I4) { ... }

@@
@@
-#define mmu_notifier_range_init(range, mm, start, end)
+#define mmu_notifier_range_init(range, event, flags, vma, mm, start, end)

@@
expression E1, E3, E4;
identifier I1;
@@
<...
mmu_notifier_range_init(E1,
+MMU_NOTIFY_UNMAP, 0, I1,
I1->vm_mm, E3, E4)
...>

@@
expression E1, E2, E3, E4;
identifier FN, VMA;
@@
FN(..., struct vm_area_struct *VMA, ...) {
<...
mmu_notifier_range_init(E1,
+MMU_NOTIFY_UNMAP, 0, VMA,
E2, E3, E4)
...> }

@@
expression E1, E2, E3, E4;
identifier FN, VMA;
@@
FN(...) {
struct vm_area_struct *VMA;
<...
mmu_notifier_range_init(E1,
+MMU_NOTIFY_UNMAP, 0, VMA,
E2, E3, E4)
...> }

@@
expression E1, E2, E3, E4;
identifier FN;
@@
FN(...) {
<...
mmu_notifier_range_init(E1,
+MMU_NOTIFY_UNMAP, 0, NULL,
E2, E3, E4)
...> }
---------------------------------------------------------------------->%

Applied with:
spatch --all-includes --sp-file mmu-notifier.spatch fs/proc/task_mmu.c --in-place
spatch --sp-file mmu-notifier.spatch --dir kernel/events/ --in-place
spatch --sp-file mmu-notifier.spatch --dir mm --in-place

Link: http://lkml.kernel.org/r/20190326164747.24405-6-jglisse@redhat.com
Signed-off-by: Jérôme Glisse 
Reviewed-by: Ralph Campbell 
Reviewed-by: Ira Weiny 
Cc: Christian König 
Cc: Joonas Lahtinen 
Cc: Jani Nikula 
Cc: Rodrigo Vivi 
Cc: Jan Kara 
Cc: Andrea Arcangeli 
Cc: Peter Xu 
Cc: Felix Kuehling 
Cc: Jason Gunthorpe 
Cc: Ross Zwisler 
Cc: Dan Williams 
Cc: Paolo Bonzini 
Cc: Radim Krcmar 
Cc: Michal Hocko 
Cc: Christian Koenig 
Cc: John Hubbard 
Cc: Arnd Bergmann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping

2019-04-19T16:46:05+00:00

The core dumping code has always run without holding the mmap_sem for
writing, despite that is the only way to ensure that the entire vma
layout will not change from under it.  Only using some signal
serialization on the processes belonging to the mm is not nearly enough.
This was pointed out earlier.  For example in Hugh's post from Jul 2017:

  https://lkml.kernel.org/r/alpine.LSU.2.11.1707191716030.2055@eggly.anvils

  "Not strictly relevant here, but a related note: I was very surprised
   to discover, only quite recently, how handle_mm_fault() may be called
   without down_read(mmap_sem) - when core dumping. That seems a
   misguided optimization to me, which would also be nice to correct"

In particular because the growsdown and growsup can move the
vm_start/vm_end the various loops the core dump does around the vma will
not be consistent if page faults can happen concurrently.

Pretty much all users calling mmget_not_zero()/get_task_mm() and then
taking the mmap_sem had the potential to introduce unexpected side
effects in the core dumping code.

Adding mmap_sem for writing around the ->core_dump invocation is a
viable long term fix, but it requires removing all copy user and page
faults and to replace them with get_dump_page() for all binary formats
which is not suitable as a short term fix.

For the time being this solution manually covers the places that can
confuse the core dump either by altering the vma layout or the vma flags
while it runs.  Once ->core_dump runs under mmap_sem for writing the
function mmget_still_valid() can be dropped.

Allowing mmap_sem protected sections to run in parallel with the
coredump provides some minor parallelism advantage to the swapoff code
(which seems to be safe enough by never mangling any vma field and can
keep doing swapins in parallel to the core dumping) and to some other
corner case.

In order to facilitate the backporting I added "Fixes: 86039bd3b4e6"
however the side effect of this same race condition in /proc/pid/mem
should be reproducible since before 2.6.12-rc2 so I couldn't add any
other "Fixes:" because there's no hash beyond the git genesis commit.

Because find_extend_vma() is the only location outside of the process
context that could modify the "mm" structures under mmap_sem for
reading, by adding the mmget_still_valid() check to it, all other cases
that take the mmap_sem for reading don't need the new check after
mmget_not_zero()/get_task_mm().  The expand_stack() in page fault
context also doesn't need the new check, because all tasks under core
dumping are frozen.

Link: http://lkml.kernel.org/r/20190325224949.11068-1-aarcange@redhat.com
Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization")
Signed-off-by: Andrea Arcangeli 
Reported-by: Jann Horn 
Suggested-by: Oleg Nesterov 
Acked-by: Peter Xu 
Reviewed-by: Mike Rapoport 
Reviewed-by: Oleg Nesterov 
Reviewed-by: Jann Horn 
Acked-by: Jason Gunthorpe 
Acked-by: Michal Hocko 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

2019-03-09T23:53:03+00:00

Pull rdma updates from Jason Gunthorpe:
 "This has been a slightly more active cycle than normal with ongoing
  core changes and quite a lot of collected driver updates.

   - Various driver fixes for bnxt_re, cxgb4, hns, mlx5, pvrdma, rxe

   - A new data transfer mode for HFI1 giving higher performance

   - Significant functional and bug fix update to the mlx5
     On-Demand-Paging MR feature

   - A chip hang reset recovery system for hns

   - Change mm->pinned_vm to an atomic64

   - Update bnxt_re to support a new 57500 chip

   - A sane netlink 'rdma link add' method for creating rxe devices and
     fixing the various unregistration race conditions in rxe's
     unregister flow

   - Allow lookup up objects by an ID over netlink

   - Various reworking of the core to driver interface:
       - drivers should not assume umem SGLs are in PAGE_SIZE chunks
       - ucontext is accessed via udata not other means
       - start to make the core code responsible for object memory
         allocation
       - drivers should convert struct device to struct ib_device via a
         helper
       - drivers have more tools to avoid use after unregister problems"

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (280 commits)
  net/mlx5: ODP support for XRC transport is not enabled by default in FW
  IB/hfi1: Close race condition on user context disable and close
  RDMA/umem: Revert broken 'off by one' fix
  RDMA/umem: minor bug fix in error handling path
  RDMA/hns: Use GFP_ATOMIC in hns_roce_v2_modify_qp
  cxgb4: kfree mhp after the debug print
  IB/rdmavt: Fix concurrency panics in QP post_send and modify to error
  IB/rdmavt: Fix loopback send with invalidate ordering
  IB/iser: Fix dma_nents type definition
  IB/mlx5: Set correct write permissions for implicit ODP MR
  bnxt_re: Clean cq for kernel consumers only
  RDMA/uverbs: Don't do double free of allocated PD
  RDMA: Handle ucontext allocations by IB/core
  RDMA/core: Fix a WARN() message
  bnxt_re: fix the regression due to changes in alloc_pbl
  IB/mlx4: Increase the timeout for CM cache
  IB/core: Abort page fault handler silently during owning process exit
  IB/mlx5: Validate correct PD before prefetch MR
  IB/mlx5: Protect against prefetch of invalid MR
  RDMA/uverbs: Store PR pointer before it is overwritten
  ...

mm: update ptep_modify_prot_commit to take old pte value as arg

2019-03-06T05:07:18+00:00

Architectures like ppc64 require to do a conditional tlb flush based on
the old and new value of pte.  Enable that by passing old pte value as
the arg.

Link: http://lkml.kernel.org/r/20190116085035.29729-3-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Cc: Benjamin Herrenschmidt 
Cc: Heiko Carstens 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Martin Schwidefsky 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Paul Mackerras 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: update ptep_modify_prot_start/commit to take vm_area_struct as arg

2019-03-06T05:07:18+00:00

Patch series "NestMMU pte upgrade workaround for mprotect", v5.

We can upgrade pte access (R -> RW transition) via mprotect.  We need to
make sure we follow the recommended pte update sequence as outlined in
commit bd5050e38aec ("powerpc/mm/radix: Change pte relax sequence to
handle nest MMU hang") for such updates.  This patch series does that.

This patch (of 5):

Some architectures may want to call flush_tlb_range from these helpers.

Link: http://lkml.kernel.org/r/20190116085035.29729-2-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Cc: Nicholas Piggin 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Heiko Carstens 
Cc: Martin Schwidefsky 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds