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  1. 25 Jun, 2019 32 commits
  3. 22 Jun, 2019 8 commits
    • Greg Kroah-Hartman's avatar
      Linux 5.1.14 · 5f0a74b4
      Greg Kroah-Hartman authored
      5f0a74b4
    • Eric Dumazet's avatar
      tcp: refine memory limit test in tcp_fragment() · b27f2c88
      Eric Dumazet authored 
      commit b6653b36 upstream.

tcp_fragment() might be called for skbs in the write queue.

Memory limits might have been exceeded because tcp_sendmsg() only
checks limits at full skb (64KB) boundaries.

Therefore, we need to make sure tcp_fragment() wont punish applications
that might have setup very low SO_SNDBUF values.

Fixes: f070ef2a ("tcp: tcp_fragment() should apply sane memory limits")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarChristoph Paasch <cpaasch@apple.com>
Tested-by: default avatarChristoph Paasch <cpaasch@apple.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b27f2c88
    • Greg Kroah-Hartman's avatar
      Linux 5.1.13 · 7da3d9e6
      Greg Kroah-Hartman authored
      7da3d9e6
    • Andrea Arcangeli's avatar
      coredump: fix race condition between collapse_huge_page() and core dumping · d7dcfd25
      Andrea Arcangeli authored 
      commit 59ea6d06 upstream.

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 04f5866e ("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: ba76149f ("thp: khugepaged")
Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Reported-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      d7dcfd25
    • Sagi Grimberg's avatar
      nvme-tcp: fix queue mapping when queue count is limited · 3111e132
      Sagi Grimberg authored 
      commit 64861993 upstream.

When the controller supports less queues than requested, we
should make sure that queue mapping does the right thing and
not assume that all queues are available. This fixes a crash
when the controller supports less queues than requested.

The rules are:
1. if no write queues are requested, we assign the available queues
   to the default queue map. The default and read queue maps share the
   existing queues.
2. if write queues are requested:
  - first make sure that read queue map gets the requested
    nr_io_queues count
  - then grant the default queue map the minimum between the requested
    nr_write_queues and the remaining queues. If there are no available
    queues to dedicate to the default queue map, fallback to (1) and
    share all the queues in the existing queue map.

Also, provide a log indication on how we constructed the different
queue maps.
Reported-by: default avatarHarris, James R <james.r.harris@intel.com>
Tested-by: default avatarJim Harris <james.r.harris@intel.com>
Cc: <stable@vger.kernel.org> # v5.0+
Suggested-by: default avatarRoy Shterman <roys@lightbitslabs.com>
Signed-off-by: default avatarSagi Grimberg <sagi@grimberg.me>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3111e132
    • Sagi Grimberg's avatar
      nvme-tcp: fix possible null deref on a timed out io queue connect · d28c4813
      Sagi Grimberg authored 
      commit f34e2589 upstream.

If I/O queue connect times out, we might have freed the queue socket
already, so check for that on the error path in nvme_tcp_start_queue.
Signed-off-by: default avatarSagi Grimberg <sagi@grimberg.me>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      d28c4813
    • Sagi Grimberg's avatar
      nvme-tcp: rename function to have nvme_tcp prefix · bd445693
      Sagi Grimberg authored 
      commit efb973b1 upstream.

usually nvme_ prefix is for core functions.
While we're cleaning up, remove redundant empty lines
Signed-off-by: default avatarSagi Grimberg <sagi@grimberg.me>
Reviewed-by: default avatarMinwoo Im <minwoo.im@samsung.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      bd445693
    • Yang Shi's avatar
      mm: mmu_gather: remove __tlb_reset_range() for force flush · b936bac3
      Yang Shi authored 
      commit 7a30df49 upstream.

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 dd2283f2 ("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-gbec7550c
--------------------------
         mean     stddev
real    37.382   2.780
user     1.420   0.078
sys     54.658   1.855

v5.2-rc2-24-gbec7550c + "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: dd2283f2 ("mm: mmap: zap pages with read mmap_sem in munmap")
Signed-off-by: default avatarYang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: default avatarJan Stancek <jstancek@redhat.com>
Reported-by: default avatarJan Stancek <jstancek@redhat.com>
Tested-by: default avatarJan Stancek <jstancek@redhat.com>
Suggested-by: default avatarWill Deacon <will.deacon@arm.com>
Tested-by: default avatarWill Deacon <will.deacon@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: <stable@vger.kernel.org>	[4.20+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b936bac3
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