Linux v4.15.10

Fix for dock booting (rhbz 1549042)
Fix THP bug (rhbz 1546709)

1 files changed, 51 insertions, 0 deletions

diff --git a/mm-khugepaged-Convert-VM_BUG_ON-to-collapse-fail.patch b/mm-khugepaged-Convert-VM_BUG_ON-to-collapse-fail.patch
new file mode 100644
index 000000000..c5d3a0c0c
--- /dev/null
+++ b/mm-khugepaged-Convert-VM_BUG_ON-to-collapse-fail.patch
@@ -0,0 +1,51 @@
+From patchwork Thu Mar 15 15:23:53 2018
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: mm/khugepaged: Convert VM_BUG_ON() to collapse fail
+From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
+X-Patchwork-Id: 10284785
+Message-Id: <20180315152353.27989-1-kirill.shutemov@linux.intel.com>
+To: Andrew Morton <akpm@linux-foundation.org>
+Cc: Laura Abbott <labbott@redhat.com>, linux-mm@kvack.org,
+ linux-kernel@vger.kernel.org,
+ "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
+Date: Thu, 15 Mar 2018 18:23:53 +0300
+
+khugepaged is not yet able to convert PTE-mapped huge pages back to PMD
+mapped. We do not collapse such pages. See check khugepaged_scan_pmd().
+
+But if between khugepaged_scan_pmd() and __collapse_huge_page_isolate()
+somebody managed to instantiate THP in the range and then split the PMD
+back to PTEs we would have a problem -- VM_BUG_ON_PAGE(PageCompound(page))
+will get triggered.
+
+It's possible since we drop mmap_sem during collapse to re-take for
+write.
+
+Replace the VM_BUG_ON() with graceful collapse fail.
+
+Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Fixes: b1caa957ae6d ("khugepaged: ignore pmd tables with THP mapped with ptes")
+---
+ mm/khugepaged.c | 7 ++++++-
+ 1 file changed, 6 insertions(+), 1 deletion(-)
+
+diff --git a/mm/khugepaged.c b/mm/khugepaged.c
+index b7e2268dfc9a..c15da1ea7e63 100644
+--- a/mm/khugepaged.c
++++ b/mm/khugepaged.c
+@@ -530,7 +530,12 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
+ 			goto out;
+ 		}
+ 
+-		VM_BUG_ON_PAGE(PageCompound(page), page);
++		/* TODO: teach khugepaged to collapse THP mapped with pte */
++		if (PageCompound(page)) {
++			result = SCAN_PAGE_COMPOUND;
++			goto out;
++		}
++
+ 		VM_BUG_ON_PAGE(!PageAnon(page), page);
+ 
+ 		/*