* [merged mm-stable] nodemaskh-fix-compilation-error-with-gcc12.patch removed from -mm tree
@ 2022-05-19 22:26 Andrew Morton
0 siblings, 0 replies; only message in thread
From: Andrew Morton @ 2022-05-19 22:26 UTC (permalink / raw)
To: mm-commits, vincent.guittot, thunder.leizhen, stable, rostedt,
peterz, pbonzini, mst, mingo, mgorman, juri.lelli, jasowang,
dietmar.eggemann, christophe, bsegall, bristot, akpm, dinechin,
akpm
The quilt patch titled
Subject: nodemask.h: fix compilation error with GCC12
has been removed from the -mm tree. Its filename was
nodemaskh-fix-compilation-error-with-gcc12.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Christophe de Dinechin <dinechin@redhat.com>
Subject: nodemask.h: fix compilation error with GCC12
Date: Thu, 14 Apr 2022 17:08:54 +0200
With gcc version 12.0.1 20220401 (Red Hat 12.0.1-0), building with
defconfig results in the following compilation error:
| CC mm/swapfile.o
| mm/swapfile.c: In function `setup_swap_info':
| mm/swapfile.c:2291:47: error: array subscript -1 is below array bounds
| of `struct plist_node[]' [-Werror=array-bounds]
| 2291 | p->avail_lists[i].prio = 1;
| | ~~~~~~~~~~~~~~^~~
| In file included from mm/swapfile.c:16:
| ./include/linux/swap.h:292:27: note: while referencing `avail_lists'
| 292 | struct plist_node avail_lists[]; /*
| | ^~~~~~~~~~~
This is due to the compiler detecting that the mask in
node_states[__state] could theoretically be zero, which would lead to
first_node() returning -1 through find_first_bit.
I believe that the warning/error is legitimate. I first tried adding a
test to check that the node mask is not emtpy, since a similar test exists
in the case where MAX_NUMNODES == 1.
However, adding the if statement causes other warnings to appear in
for_each_cpu_node_but, because it introduces a dangling else ambiguity.
And unfortunately, GCC is not smart enough to detect that the added test
makes the case where (node) == -1 impossible, so it still complains with
the same message.
This is why I settled on replacing that with a harmless, but relatively
useless (node) >= 0 test. Based on the warning for the dangling else, I
also decided to fix the case where MAX_NUMNODES == 1 by moving the
condition inside the for loop. It will still only be tested once. This
ensures that the meaning of an else following for_each_node_mask or
derivatives would not silently have a different meaning depending on the
configuration.
Link: https://lkml.kernel.org/r/20220414150855.2407137-3-dinechin@redhat.com
Signed-off-by: Christophe de Dinechin <christophe@dinechin.org>
Signed-off-by: Christophe de Dinechin <dinechin@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Ben Segall <bsegall@google.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/nodemask.h | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
--- a/include/linux/nodemask.h~nodemaskh-fix-compilation-error-with-gcc12
+++ a/include/linux/nodemask.h
@@ -375,14 +375,13 @@ static inline void __nodes_fold(nodemask
}
#if MAX_NUMNODES > 1
-#define for_each_node_mask(node, mask) \
- for ((node) = first_node(mask); \
- (node) < MAX_NUMNODES; \
- (node) = next_node((node), (mask)))
+#define for_each_node_mask(node, mask) \
+ for ((node) = first_node(mask); \
+ (node >= 0) && (node) < MAX_NUMNODES; \
+ (node) = next_node((node), (mask)))
#else /* MAX_NUMNODES == 1 */
-#define for_each_node_mask(node, mask) \
- if (!nodes_empty(mask)) \
- for ((node) = 0; (node) < 1; (node)++)
+#define for_each_node_mask(node, mask) \
+ for ((node) = 0; (node) < 1 && !nodes_empty(mask); (node)++)
#endif /* MAX_NUMNODES */
/*
_
Patches currently in -mm which might be from dinechin@redhat.com are
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2022-05-19 22:26 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-19 22:26 [merged mm-stable] nodemaskh-fix-compilation-error-with-gcc12.patch removed from -mm tree Andrew Morton
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).