The patch titled
Subject: mm/vmalloc.c: avoid bogus -Wmaybe-uninitialized warning
has been added to the -mm tree. Its filename is
mm-vmalloc-avoid-bogus-wmaybe-uninitialized-warning.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-vmalloc-avoid-bogus-wmaybe-uninitialized-warning.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-vmalloc-avoid-bogus-wmaybe-uninitialized-warning.patch
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------------------------------------------------------
From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: mm/vmalloc.c: avoid bogus -Wmaybe-uninitialized warning
gcc gets confused in pcpu_get_vm_areas() because there are too many
branches that affect whether 'lva' was initialized before it gets used:
mm/vmalloc.c: In function 'pcpu_get_vm_areas':
mm/vmalloc.c:991:4: error: 'lva' may be used uninitialized in this function [-Werror=maybe-uninitialized]
insert_vmap_area_augment(lva, &va->rb_node,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
&free_vmap_area_root, &free_vmap_area_list);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/vmalloc.c:916:20: note: 'lva' was declared here
struct vmap_area *lva;
^~~
Add an intialization to NULL, and check whether this has changed
before the first use.
Link: http://lkml.kernel.org/r/20190618092650.2943749-1-arnd@xxxxxxxx
Fixes: 68ad4a330433 ("mm/vmalloc.c: keep track of free blocks for vmap allocation")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Cc: Joel Fernandes <joelaf@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmalloc.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/mm/vmalloc.c~mm-vmalloc-avoid-bogus-wmaybe-uninitialized-warning
+++ a/mm/vmalloc.c
@@ -913,7 +913,12 @@ adjust_va_to_fit_type(struct vmap_area *
unsigned long nva_start_addr, unsigned long size,
enum fit_type type)
{
- struct vmap_area *lva;
+ /*
+ * GCC cannot always keep track of whether this variable
+ * was initialized across many branches, therefore set
+ * it NULL here to avoid a warning.
+ */
+ struct vmap_area *lva = NULL;
if (type == FL_FIT_TYPE) {
/*
@@ -972,7 +977,7 @@ adjust_va_to_fit_type(struct vmap_area *
if (type != FL_FIT_TYPE) {
augment_tree_propagate_from(va);
- if (type == NE_FIT_TYPE)
+ if (lva)
insert_vmap_area_augment(lva, &va->rb_node,
&free_vmap_area_root, &free_vmap_area_list);
}
_
Patches currently in -mm which might be from arnd@xxxxxxxx are
mm-vmalloc-avoid-bogus-wmaybe-uninitialized-warning.patch
lib-test_meminit-fix-wmaybe-uninitialized-false-positive.patch
coda-stop-using-struct-timespec-in-user-api.patch
proc-sysctl-add-shared-variables-for-range-check-fix-3.patch
