Subject: + mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges.patch added to -mm tree
To: david.vrabel@xxxxxxxxxx,dietmar.hahn@xxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 11 Mar 2014 12:47:34 -0700
The patch titled
Subject: mm/vmalloc: avoid soft lockup warnings when vunmap()'ing large ranges
has been added to the -mm tree. Its filename is
mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges.patch
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------------------------------------------------------
From: David Vrabel <david.vrabel@xxxxxxxxxx>
Subject: mm/vmalloc: avoid soft lockup warnings when vunmap()'ing large ranges
If vunmap() is used to unmap a large (e.g., 50 GB) region, it may take
sufficiently long that it triggers soft lockup warnings.
Add a cond_resched() into vunmap_pmd_range() so the calling task may be
resheduled after unmapping each PMD entry. This is how zap_pmd_range()
fixes the same problem for userspace mappings.
All callers may sleep except for the APEI GHES driver (apei/ghes.c) which
calls unmap_kernel_range_no_flush() from NMI and IRQ contexts. This
driver only unmaps a single pages so don't call cond_resched() if the
unmap doesn't cross a PMD boundary.
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Reported-by: Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmalloc.c | 2 ++
1 file changed, 2 insertions(+)
diff -puN mm/vmalloc.c~mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges mm/vmalloc.c
--- a/mm/vmalloc.c~mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges
+++ a/mm/vmalloc.c
@@ -77,6 +77,8 @@ static void vunmap_pmd_range(pud_t *pud,
if (pmd_none_or_clear_bad(pmd))
continue;
vunmap_pte_range(pmd, addr, next);
+ if (next != end)
+ cond_resched();
} while (pmd++, addr = next, addr != end);
}
_
Patches currently in -mm which might be from david.vrabel@xxxxxxxxxx are
mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges.patch
mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges-fix.patch
linux-next.patch
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