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.
Reported-by: Dietmar Hahn <dietmar.h...@ts.fujitsu.com>
Signed-off-by: David Vrabel <david.vra...@citrix.com>
---
v2: don't call cond_resched() at the end of a PMD range.
---
mm/vmalloc.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 0fdf968..1a8b162 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -75,6 +75,8 @@ static void vunmap_pmd_range(pud_t *pud, unsigned long addr,
unsigned long end)
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);
}
--
1.7.2.5
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
