The patch titled
Subject: mm/mlock.c: document scary-looking stack expansion mlock chain
has been removed from the -mm tree. Its filename was
mm-mlockc-document-scary-looking-stack-expansion-mlock-chain.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm/mlock.c: document scary-looking stack expansion mlock chain
The fact that mlock calls get_user_pages, and get_user_pages might
call mlock when expanding a stack looks like a potential recursion.
However, mlock makes sure the requested range is already contained
within a vma, so no stack expansion will actually happen from mlock.
Should this ever change: the stack expansion mlocks only the newly
expanded range and so will not result in recursive expansion.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: Michel Lespinasse <walken@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mlock.c | 4 ++++
1 file changed, 4 insertions(+)
diff -puN mm/mlock.c~mm-mlockc-document-scary-looking-stack-expansion-mlock-chain mm/mlock.c
--- a/mm/mlock.c~mm-mlockc-document-scary-looking-stack-expansion-mlock-chain
+++ a/mm/mlock.c
@@ -185,6 +185,10 @@ long __mlock_vma_pages_range(struct vm_a
if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
gup_flags |= FOLL_FORCE;
+ /*
+ * We made sure addr is within a VMA, so the following will
+ * not result in a stack expansion that recurses back here.
+ */
return __get_user_pages(current, mm, addr, nr_pages, gup_flags,
NULL, NULL, nonblocking);
}
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
origin.patch
mm-memmap_init_zone-performance-improvement.patch
memcg-debugging-facility-to-access-dangling-memcgs.patch
debugging-keep-track-of-page-owners-fix-2-fix-fix-fix.patch
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