The patch titled
Subject: mm: change nr_ptes BUG_ON to WARN_ON
has been added to the -mm tree. Its filename is
mm-change-nr_ptes-bug_on-to-warn_on.patch
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------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: mm: change nr_ptes BUG_ON to WARN_ON
Occasionally an isolated BUG_ON(mm->nr_ptes) gets reported, indicating
that not all the page tables allocated could be found and freed when
exit_mmap() tore down the user address space.
There's usually nothing we can say about it, beyond that it's probably a
sign of some bad memory or memory corruption; though it might still
indicate a bug in vma or page table management (and did recently reveal a
race in THP, fixed a few months ago).
But one overdue change we can make is from BUG_ON to WARN_ON.
It's fairly likely that the system will crash shortly afterwards in some
other way (for example, the BUG_ON(page_mapped(page)) in
__delete_from_page_cache(), once an inode mapped into the lost page tables
gets evicted); but might tell us more before that.
Change the BUG_ON(page_mapped) to WARN_ON too? Later perhaps: I'm less
eager, since that one has several times led to fixes.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/mmap.c~mm-change-nr_ptes-bug_on-to-warn_on mm/mmap.c
--- a/mm/mmap.c~mm-change-nr_ptes-bug_on-to-warn_on
+++ a/mm/mmap.c
@@ -2309,7 +2309,7 @@ void exit_mmap(struct mm_struct *mm)
}
vm_unacct_memory(nr_accounted);
- BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
+ WARN_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
}
/* Insert vm structure into process list sorted by address
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
origin.patch
mm-change-nr_ptes-bug_on-to-warn_on.patch
prio_tree-debugging-patch.patch
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