mm/khugepaged: collapse_shmem() remember to clear holes
Subsystems (3)
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maintainerPATCH 26/31 mm/khugepaged: collapse_shmem() remember to clear holes
From: Hugh Dickins <[email protected]>
Subject: mm/khugepaged: collapse_shmem() remember to clear holes
Huge tmpfs testing reminds us that there is no __GFP_ZERO in the gfp flags khugepaged uses to allocate a huge page - in all common cases it would just be a waste of effort - so collapse_shmem() must remember to clear out any holes that it instantiates.
The obvious place to do so, where they are put into the page cache tree, is not a good choice: because interrupts are disabled there. Leave it until further down, once success is assured, where the other pages are copied (before setting PageUptodate).
Fixes f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by Hugh Dickins <[email protected]>
Cc Jerome Glisse <[email protected]>
Cc Konstantin Khlebnikov <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc <[email protected]> [4.8+]
Signed-off-by Andrew Morton <[email protected]>
---
mm/khugepaged.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
mm/khugepaged.c renamed from mm/khugepaged.c~mm-khugepaged-collapse_shmem-remember-to-clear-holes +10 -0
@@ -1467,7 +1467,12 @@ xa_unlocked:* Replacing old pages with new one has succeeded, now we * need to copy the content and free the old pages. */ + index = start;list_for_each_entry_safe (page, tmp, &pagelist, lru) { +while (index < page->index) { +clear_highpage (new_page + (index %HPAGE_PMD_NR )); + index++; + }copy_highpage (new_page + (page->index %HPAGE_PMD_NR ), page);list_del (&page->lru);
@@ -1477,6 +1482,11 @@ xa_unlocked:ClearPageActive (page);ClearPageUnevictable (page);put_page (page); + index++; + } +while (index < end) { +clear_highpage (new_page + (index %HPAGE_PMD_NR )); + index++; }local_irq_disable ();
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