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authorVlastimil Babka <vbabka@suse.cz>2019-01-14 10:07:57 +0100
committerVlastimil Babka <vbabka@suse.cz>2019-01-14 10:08:28 +0100
commit6fbf3d58294c7e64bac07824fa97866b4757a347 (patch)
treec8497864a5a026cf2e49ce833a47cc50d0f1b1ee
parent418db51f8b57ec33f90bc040adcae419f70667f8 (diff)
mm/khugepaged: collapse_shmem() stop if punched or truncated
(VM Functionality, bsc#1121599).
-rw-r--r--patches.fixes/mm-khugepaged-collapse_shmem-stop-if-punched-or-truncated.patch60
-rw-r--r--series.conf1
2 files changed, 61 insertions, 0 deletions
diff --git a/patches.fixes/mm-khugepaged-collapse_shmem-stop-if-punched-or-truncated.patch b/patches.fixes/mm-khugepaged-collapse_shmem-stop-if-punched-or-truncated.patch
new file mode 100644
index 0000000000..c746dde23f
--- /dev/null
+++ b/patches.fixes/mm-khugepaged-collapse_shmem-stop-if-punched-or-truncated.patch
@@ -0,0 +1,60 @@
+From: Hugh Dickins <hughd@google.com>
+Date: Fri, 30 Nov 2018 14:10:25 -0800
+Subject: mm/khugepaged: collapse_shmem() stop if punched or truncated
+Git-commit: 701270fa193aadf00bdcf607738f64997275d4c7
+Patch-mainline: v4.20-rc5
+References: VM Functionality, bsc#1121599
+
+[ vbabka@suse.cz: use the 4.14 pre-xarray stable backport ]
+
+Huge tmpfs testing showed that although collapse_shmem() recognizes a
+concurrently truncated or hole-punched page correctly, its handling of
+holes was liable to refill an emptied extent. Add check to stop that.
+
+Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261522040.2275@eggly.anvils
+Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Reviewed-by: Matthew Wilcox <willy@infradead.org>
+Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Jerome Glisse <jglisse@redhat.com>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Cc: <stable@vger.kernel.org> [4.8+]
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
+---
+ mm/khugepaged.c | 15 +++++++++++++++
+ 1 file changed, 15 insertions(+)
+
+--- a/mm/khugepaged.c
++++ b/mm/khugepaged.c
+@@ -1348,6 +1348,16 @@ static void collapse_shmem(struct mm_str
+ int n = min(iter.index, end) - index;
+
+ /*
++ * Stop if extent has been hole-punched, and is now completely
++ * empty (the more obvious i_size_read() check would take an
++ * irq-unsafe seqlock on 32-bit).
++ */
++ if (n >= HPAGE_PMD_NR) {
++ result = SCAN_TRUNCATED;
++ goto tree_locked;
++ }
++
++ /*
+ * Handle holes in the radix tree: charge it from shmem and
+ * insert relevant subpage of new_page into the radix-tree.
+ */
+@@ -1458,6 +1468,11 @@ out_unlock:
+ if (result == SCAN_SUCCEED && index < end) {
+ int n = end - index;
+
++ /* Stop if extent has been truncated, and is now empty */
++ if (n >= HPAGE_PMD_NR) {
++ result = SCAN_TRUNCATED;
++ goto tree_locked;
++ }
+ if (!shmem_charge(mapping->host, n)) {
+ result = SCAN_FAIL;
+ goto tree_locked;
diff --git a/series.conf b/series.conf
index 6c64b90dca..e61800fbe1 100644
--- a/series.conf
+++ b/series.conf
@@ -19366,6 +19366,7 @@
patches.fixes/mm-huge_memory-rename-freeze_page-to-unmap_page.patch
patches.fixes/mm-huge_memory-splitting-set-mapping-index-before-unfreeze.patch
patches.fixes/mm-huge_memory-fix-lockdep-complaint-on-32-bit-i_size_read.patch
+ patches.fixes/mm-khugepaged-collapse_shmem-stop-if-punched-or-truncated.patch
patches.drivers/pci-imx6-fix-link-training-status-detection-in-link-up-check
patches.fixes/fs-fix-lost-error-code-in-dio_complete.patch
patches.fixes/nvme-free-ctrl-device-name-on-init-failure.patch