linux.git/mm, branch v5.2-rc6

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Enrico Weigelt 
Reviewed-by: Kate Stewart 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 499

2019-06-19T15:09:53+00:00

Based on 1 normalized pattern(s):

  this work is licensed under the terms of the gnu gpl version 2 see
  the copying file in the top level directory

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 35 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Kate Stewart 
Reviewed-by: Enrico Weigelt 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.797835076@linutronix.de
Signed-off-by: Greg Kroah-Hartman

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 482

2019-06-19T15:09:52+00:00

Based on 1 normalized pattern(s):

  this work is licensed under the terms of the gnu gpl version 2

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 48 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Reviewed-by: Enrico Weigelt 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081204.624030236@linutronix.de
Signed-off-by: Greg Kroah-Hartman

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 248

2019-06-19T15:09:08+00:00

Based on 1 normalized pattern(s):

  this file is released under the gpl v2

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 3 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Alexios Zavras 
Reviewed-by: Allison Randal 
Reviewed-by: Armijn Hemel 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204655.103854853@linutronix.de
Signed-off-by: Greg Kroah-Hartman

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-06-16T17:28:14+00:00

Pull x86 fixes from Thomas Gleixner:
 "The accumulated fixes from this and last week:

   - Fix vmalloc TLB flush and map range calculations which lead to
     stale TLBs, spurious faults and other hard to diagnose issues.

   - Use fault_in_pages_writable() for prefaulting the user stack in the
     FPU code as it's less fragile than the current solution

   - Use the PF_KTHREAD flag when checking for a kernel thread instead
     of current->mm as the latter can give the wrong answer due to
     use_mm()

   - Compute the vmemmap size correctly for KASLR and 5-Level paging.
     Otherwise this can end up with a way too small vmemmap area.

   - Make KASAN and 5-level paging work again by making sure that all
     invalid bits are masked out when computing the P4D offset. This
     worked before but got broken recently when the LDT remap area was
     moved.

   - Prevent a NULL pointer dereference in the resource control code
     which can be triggered with certain mount options when the
     requested resource is not available.

   - Enforce ordering of microcode loading vs. perf initialization on
     secondary CPUs. Otherwise perf tries to access a non-existing MSR
     as the boot CPU marked it as available.

   - Don't stop the resource control group walk early otherwise the
     control bitmaps are not updated correctly and become inconsistent.

   - Unbreak kgdb by returning 0 on success from
     kgdb_arch_set_breakpoint() instead of an error code.

   - Add more Icelake CPU model defines so depending changes can be
     queued in other trees"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/microcode, cpuhotplug: Add a microcode loader CPU hotplug callback
  x86/kasan: Fix boot with 5-level paging and KASAN
  x86/fpu: Don't use current->mm to check for a kthread
  x86/kgdb: Return 0 from kgdb_arch_set_breakpoint()
  x86/resctrl: Prevent NULL pointer dereference when local MBM is disabled
  x86/resctrl: Don't stop walking closids when a locksetup group is found
  x86/fpu: Update kernel's FPU state before using for the fsave header
  x86/mm/KASLR: Compute the size of the vmemmap section properly
  x86/fpu: Use fault_in_pages_writeable() for pre-faulting
  x86/CPU: Add more Icelake model numbers
  mm/vmalloc: Avoid rare case of flushing TLB with weird arguments
  mm/vmalloc: Fix calculation of direct map addr range

mm/devm_memremap_pages: fix final page put race

2019-06-14T03:34:56+00:00

Logan noticed that devm_memremap_pages_release() kills the percpu_ref
drops all the page references that were acquired at init and then
immediately proceeds to unplug, arch_remove_memory(), the backing pages
for the pagemap.  If for some reason device shutdown actually collides
with a busy / elevated-ref-count page then arch_remove_memory() should
be deferred until after that reference is dropped.

As it stands the "wait for last page ref drop" happens *after*
devm_memremap_pages_release() returns, which is obviously too late and
can lead to crashes.

Fix this situation by assigning the responsibility to wait for the
percpu_ref to go idle to devm_memremap_pages() with a new ->cleanup()
callback.  Implement the new cleanup callback for all
devm_memremap_pages() users: pmem, devdax, hmm, and p2pdma.

Link: http://lkml.kernel.org/r/155727339156.292046.5432007428235387859.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 41e94a851304 ("add devm_memremap_pages")
Signed-off-by: Dan Williams 
Reported-by: Logan Gunthorpe 
Reviewed-by: Ira Weiny 
Reviewed-by: Logan Gunthorpe 
Cc: Bjorn Helgaas 
Cc: "Jérôme Glisse" 
Cc: Christoph Hellwig 
Cc: Greg Kroah-Hartman 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/vmscan.c: fix trying to reclaim unevictable LRU page

2019-06-14T03:34:56+00:00

There was the below bug report from Wu Fangsuo.

On the CMA allocation path, isolate_migratepages_range() could isolate
unevictable LRU pages and reclaim_clean_page_from_list() can try to
reclaim them if they are clean file-backed pages.

  page:ffffffbf02f33b40 count:86 mapcount:84 mapping:ffffffc08fa7a810 index:0x24
  flags: 0x19040c(referenced|uptodate|arch_1|mappedtodisk|unevictable|mlocked)
  raw: 000000000019040c ffffffc08fa7a810 0000000000000024 0000005600000053
  raw: ffffffc009b05b20 ffffffc009b05b20 0000000000000000 ffffffc09bf3ee80
  page dumped because: VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page))
  page->mem_cgroup:ffffffc09bf3ee80
  ------------[ cut here ]------------
  kernel BUG at /home/build/farmland/adroid9.0/kernel/linux/mm/vmscan.c:1350!
  Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
  Modules linked in:
  CPU: 0 PID: 7125 Comm: syz-executor Tainted: G S              4.14.81 #3
  Hardware name: ASR AQUILAC EVB (DT)
  task: ffffffc00a54cd00 task.stack: ffffffc009b00000
  PC is at shrink_page_list+0x1998/0x3240
  LR is at shrink_page_list+0x1998/0x3240
  pc : [] lr : [] pstate: 60400045
  sp : ffffffc009b05940
  ..
     shrink_page_list+0x1998/0x3240
     reclaim_clean_pages_from_list+0x3c0/0x4f0
     alloc_contig_range+0x3bc/0x650
     cma_alloc+0x214/0x668
     ion_cma_allocate+0x98/0x1d8
     ion_alloc+0x200/0x7e0
     ion_ioctl+0x18c/0x378
     do_vfs_ioctl+0x17c/0x1780
     SyS_ioctl+0xac/0xc0

Wu found it's due to commit ad6b67041a45 ("mm: remove SWAP_MLOCK in
ttu").  Before that, unevictable pages go to cull_mlocked so that we
can't reach the VM_BUG_ON_PAGE line.

To fix the issue, this patch filters out unevictable LRU pages from the
reclaim_clean_pages_from_list in CMA.

Link: http://lkml.kernel.org/r/20190524071114.74202-1-minchan@kernel.org
Fixes: ad6b67041a45 ("mm: remove SWAP_MLOCK in ttu")
Signed-off-by: Minchan Kim 
Reported-by: Wu Fangsuo 
Debugged-by: Wu Fangsuo 
Tested-by: Wu Fangsuo 
Reviewed-by: Andrew Morton 
Acked-by: Michal Hocko 
Cc: Pankaj Suryawanshi 
Cc: 	[4.12+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

coredump: fix race condition between collapse_huge_page() and core dumping

2019-06-14T03:34:56+00:00

When fixing the race conditions between the coredump and the mmap_sem
holders outside the context of the process, we focused on
mmget_not_zero()/get_task_mm() callers in 04f5866e41fb70 ("coredump: fix
race condition between mmget_not_zero()/get_task_mm() and core
dumping"), but those aren't the only cases where the mmap_sem can be
taken outside of the context of the process as Michal Hocko noticed
while backporting that commit to older -stable kernels.

If mmgrab() is called in the context of the process, but then the
mm_count reference is transferred outside the context of the process,
that can also be a problem if the mmap_sem has to be taken for writing
through that mm_count reference.

khugepaged registration calls mmgrab() in the context of the process,
but the mmap_sem for writing is taken later in the context of the
khugepaged kernel thread.

collapse_huge_page() after taking the mmap_sem for writing doesn't
modify any vma, so it's not obvious that it could cause a problem to the
coredump, but it happens to modify the pmd in a way that breaks an
invariant that pmd_trans_huge_lock() relies upon.  collapse_huge_page()
needs the mmap_sem for writing just to block concurrent page faults that
call pmd_trans_huge_lock().

Specifically the invariant that "!pmd_trans_huge()" cannot become a
"pmd_trans_huge()" doesn't hold while collapse_huge_page() runs.

The coredump will call __get_user_pages() without mmap_sem for reading,
which eventually can invoke a lockless page fault which will need a
functional pmd_trans_huge_lock().

So collapse_huge_page() needs to use mmget_still_valid() to check it's
not running concurrently with the coredump...  as long as the coredump
can invoke page faults without holding the mmap_sem for reading.

This has "Fixes: khugepaged" to facilitate backporting, but in my view
it's more a bug in the coredump code that will eventually have to be
rewritten to stop invoking page faults without the mmap_sem for reading.
So the long term plan is still to drop all mmget_still_valid().

Link: http://lkml.kernel.org/r/20190607161558.32104-1-aarcange@redhat.com
Fixes: ba76149f47d8 ("thp: khugepaged")
Signed-off-by: Andrea Arcangeli 
Reported-by: Michal Hocko 
Acked-by: Michal Hocko 
Acked-by: Kirill A. Shutemov 
Cc: Oleg Nesterov 
Cc: Jann Horn 
Cc: Hugh Dickins 
Cc: Mike Rapoport 
Cc: Mike Kravetz 
Cc: Peter Xu 
Cc: Jason Gunthorpe 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/mlock.c: change count_mm_mlocked_page_nr return type

2019-06-14T03:34:56+00:00

On a 64-bit machine the value of "vma->vm_end - vma->vm_start" may be
negative when using 32 bit ints and the "count >> PAGE_SHIFT"'s result
will be wrong.  So change the local variable and return value to
unsigned long to fix the problem.

Link: http://lkml.kernel.org/r/20190513023701.83056-1-swkhack@gmail.com
Fixes: 0cf2f6f6dc60 ("mm: mlock: check against vma for actual mlock() size")
Signed-off-by: swkhack 
Acked-by: Michal Hocko 
Reviewed-by: Andrew Morton 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: mmu_gather: remove __tlb_reset_range() for force flush

2019-06-14T03:34:56+00:00

A few new fields were added to mmu_gather to make TLB flush smarter for
huge page by telling what level of page table is changed.

__tlb_reset_range() is used to reset all these page table state to
unchanged, which is called by TLB flush for parallel mapping changes for
the same range under non-exclusive lock (i.e.  read mmap_sem).

Before commit dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in
munmap"), the syscalls (e.g.  MADV_DONTNEED, MADV_FREE) which may update
PTEs in parallel don't remove page tables.  But, the forementioned
commit may do munmap() under read mmap_sem and free page tables.  This
may result in program hang on aarch64 reported by Jan Stancek.  The
problem could be reproduced by his test program with slightly modified
below.

---8<---

static int map_size = 4096;
static int num_iter = 500;
static long threads_total;

static void *distant_area;

void *map_write_unmap(void *ptr)
{
	int *fd = ptr;
	unsigned char *map_address;
	int i, j = 0;

	for (i = 0; i < num_iter; i++) {
		map_address = mmap(distant_area, (size_t) map_size, PROT_WRITE | PROT_READ,
			MAP_SHARED | MAP_ANONYMOUS, -1, 0);
		if (map_address == MAP_FAILED) {
			perror("mmap");
			exit(1);
		}

		for (j = 0; j < map_size; j++)
			map_address[j] = 'b';

		if (munmap(map_address, map_size) == -1) {
			perror("munmap");
			exit(1);
		}
	}

	return NULL;
}

void *dummy(void *ptr)
{
	return NULL;
}

int main(void)
{
	pthread_t thid[2];

	/* hint for mmap in map_write_unmap() */
	distant_area = mmap(0, DISTANT_MMAP_SIZE, PROT_WRITE | PROT_READ,
			MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
	munmap(distant_area, (size_t)DISTANT_MMAP_SIZE);
	distant_area += DISTANT_MMAP_SIZE / 2;

	while (1) {
		pthread_create(&thid[0], NULL, map_write_unmap, NULL);
		pthread_create(&thid[1], NULL, dummy, NULL);

		pthread_join(thid[0], NULL);
		pthread_join(thid[1], NULL);
	}
}
---8<---

The program may bring in parallel execution like below:

        t1                                        t2
munmap(map_address)
  downgrade_write(&mm->mmap_sem);
  unmap_region()
  tlb_gather_mmu()
    inc_tlb_flush_pending(tlb->mm);
  free_pgtables()
    tlb->freed_tables = 1
    tlb->cleared_pmds = 1

                                        pthread_exit()
                                        madvise(thread_stack, 8M, MADV_DONTNEED)
                                          zap_page_range()
                                            tlb_gather_mmu()
                                              inc_tlb_flush_pending(tlb->mm);

  tlb_finish_mmu()
    if (mm_tlb_flush_nested(tlb->mm))
      __tlb_reset_range()

__tlb_reset_range() would reset freed_tables and cleared_* bits, but this
may cause inconsistency for munmap() which do free page tables.  Then it
may result in some architectures, e.g.  aarch64, may not flush TLB
completely as expected to have stale TLB entries remained.

Use fullmm flush since it yields much better performance on aarch64 and
non-fullmm doesn't yields significant difference on x86.

The original proposed fix came from Jan Stancek who mainly debugged this
issue, I just wrapped up everything together.

Jan's testing results:

v5.2-rc2-24-gbec7550cca10
--------------------------
         mean     stddev
real    37.382   2.780
user     1.420   0.078
sys     54.658   1.855

v5.2-rc2-24-gbec7550cca10 + "mm: mmu_gather: remove __tlb_reset_range() for force flush"
---------------------------------------------------------------------------------------_
         mean     stddev
real    37.119   2.105
user     1.548   0.087
sys     55.698   1.357

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1558322252-113575-1-git-send-email-yang.shi@linux.alibaba.com
Fixes: dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap")
Signed-off-by: Yang Shi 
Signed-off-by: Jan Stancek 
Reported-by: Jan Stancek 
Tested-by: Jan Stancek 
Suggested-by: Will Deacon 
Tested-by: Will Deacon 
Acked-by: Will Deacon 
Cc: Peter Zijlstra 
Cc: Nick Piggin 
Cc: "Aneesh Kumar K.V" 
Cc: Nadav Amit 
Cc: Minchan Kim 
Cc: Mel Gorman 
Cc: 	[4.20+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds