[PATCH v3 0/8] Backported fixes for 4.4 stable tree

[Ajay Kaher]

These patches include few backported fixes for the 4.4 stable
tree.
I would appreciate if you could kindly consider including them in the
next release.

Ajay

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[Changes from v2]:
Merged following changes from Vlastimil's series [1]:
- Added page_ref_count() in [Patch v3 5/8]
- Added missing refcount overflow checks on x86 and s390 [Patch v3 5/8]
- Added [Patch v3 8/8]
- Removed 7aef4172c795 i.e. [Patch v2 3/8]

[1] https://lore.kernel.org/stable/20191108093814.16032-1-vbabka@xxxxxxx/

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[PATCH v3 1/8]:
Backporting of upstream commit f958d7b528b1:
mm: make page ref count overflow check tighter and more explicit

[PATCH v3 2/8]:
Backporting of upstream commit 88b1a17dfc3e:
mm: add 'try_get_page()' helper function

[PATCH v3 3/8]:
Backporting of upstream commit a3e328556d41:
mm, gup: remove broken VM_BUG_ON_PAGE compound check for hugepages

[PATCH v3 4/8]:
Backporting of upstream commit d63206ee32b6:
mm, gup: ensure real head page is ref-counted when using hugepages

[PATCH v3 5/8]:
Backporting of upstream commit 8fde12ca79af:
mm: prevent get_user_pages() from overflowing page refcount

[PATCH v3 6/8]:
Backporting of upstream commit 7bf2d1df8082:
pipe: add pipe_buf_get() helper

[PATCH v3 7/8]:
Backporting of upstream commit 15fab63e1e57:
fs: prevent page refcount overflow in pipe_buf_get

[PATCH v3 8/8]:
x86, mm, gup: prevent get_page() race with munmap in paravirt guest