* [PATCH v2] zswap: Avoid uninitialized use of ret in zswap_frontswap_store()
@ 2023-06-01 18:34 Nathan Chancellor
2023-06-01 18:35 ` Yosry Ahmed
0 siblings, 1 reply; 3+ messages in thread
From: Nathan Chancellor @ 2023-06-01 18:34 UTC (permalink / raw)
To: akpm, sjenning, ddstreet, vitaly.wool
Cc: nphamcs, yosryahmed, ndesaulniers, trix, linux-mm, llvm, patches,
kernel test robot, Nathan Chancellor
Clang warns:
mm/zswap.c:1183:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
1183 | if (objcg && !obj_cgroup_may_zswap(objcg))
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/zswap.c:1327:9: note: uninitialized use occurs here
1327 | return ret;
| ^~~
mm/zswap.c:1183:2: note: remove the 'if' if its condition is always false
1183 | if (objcg && !obj_cgroup_may_zswap(objcg))
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1184 | goto reject;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/zswap.c:1158:9: note: initialize the variable 'ret' to silence this warning
1158 | int ret;
| ^
| = 0
1 error generated.
This condition used to return -ENOMEM by going to the shrink label, so
set ret to -ENOMEM in the if block explicitly to avoid using it
uninitialized.
Fixes: 6804144bf1cf ("zswap: do not shrink if cgroup may not zswap")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/202306011435.2BxsHFUE-lkp@intel.com/
Closes: https://lore.kernel.org/202306012152.o4FL7Y6J-lkp@intel.com/
Closes: https://github.com/ClangBuiltLinux/linux/issues/1861
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Changes in v2:
- Change ret to -ENOMEM to match this condition's previous return value
(Yosry)
- Link to v1: https://lore.kernel.org/r/20230601-zswap-cgroup-wsometimes-uninitialized-v1-1-35debdd19293@kernel.org
---
mm/zswap.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/zswap.c b/mm/zswap.c
index cff93643a6ab..30092d9a3b23 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1180,8 +1180,10 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
* local cgroup limits.
*/
objcg = get_obj_cgroup_from_page(page);
- if (objcg && !obj_cgroup_may_zswap(objcg))
+ if (objcg && !obj_cgroup_may_zswap(objcg)) {
+ ret = -ENOMEM;
goto reject;
+ }
/* reclaim space if needed */
if (zswap_is_full()) {
---
base-commit: b2424568bd9b947b2698b693ff24fec63bb4b36a
change-id: 20230601-zswap-cgroup-wsometimes-uninitialized-b549ff4247ed
Best regards,
--
Nathan Chancellor <nathan@kernel.org>
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2] zswap: Avoid uninitialized use of ret in zswap_frontswap_store()
2023-06-01 18:34 [PATCH v2] zswap: Avoid uninitialized use of ret in zswap_frontswap_store() Nathan Chancellor
@ 2023-06-01 18:35 ` Yosry Ahmed
2023-06-01 19:21 ` Nhat Pham
0 siblings, 1 reply; 3+ messages in thread
From: Yosry Ahmed @ 2023-06-01 18:35 UTC (permalink / raw)
To: Nathan Chancellor
Cc: akpm, sjenning, ddstreet, vitaly.wool, nphamcs, ndesaulniers,
trix, linux-mm, llvm, patches, kernel test robot
On Thu, Jun 1, 2023 at 11:34 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> Clang warns:
>
> mm/zswap.c:1183:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> 1183 | if (objcg && !obj_cgroup_may_zswap(objcg))
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> mm/zswap.c:1327:9: note: uninitialized use occurs here
> 1327 | return ret;
> | ^~~
> mm/zswap.c:1183:2: note: remove the 'if' if its condition is always false
> 1183 | if (objcg && !obj_cgroup_may_zswap(objcg))
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 1184 | goto reject;
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~
> mm/zswap.c:1158:9: note: initialize the variable 'ret' to silence this warning
> 1158 | int ret;
> | ^
> | = 0
> 1 error generated.
>
> This condition used to return -ENOMEM by going to the shrink label, so
> set ret to -ENOMEM in the if block explicitly to avoid using it
> uninitialized.
>
> Fixes: 6804144bf1cf ("zswap: do not shrink if cgroup may not zswap")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/202306011435.2BxsHFUE-lkp@intel.com/
> Closes: https://lore.kernel.org/202306012152.o4FL7Y6J-lkp@intel.com/
> Closes: https://github.com/ClangBuiltLinux/linux/issues/1861
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Thanks!
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
> ---
> Changes in v2:
> - Change ret to -ENOMEM to match this condition's previous return value
> (Yosry)
> - Link to v1: https://lore.kernel.org/r/20230601-zswap-cgroup-wsometimes-uninitialized-v1-1-35debdd19293@kernel.org
> ---
> mm/zswap.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index cff93643a6ab..30092d9a3b23 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -1180,8 +1180,10 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
> * local cgroup limits.
> */
> objcg = get_obj_cgroup_from_page(page);
> - if (objcg && !obj_cgroup_may_zswap(objcg))
> + if (objcg && !obj_cgroup_may_zswap(objcg)) {
> + ret = -ENOMEM;
> goto reject;
> + }
>
> /* reclaim space if needed */
> if (zswap_is_full()) {
>
> ---
> base-commit: b2424568bd9b947b2698b693ff24fec63bb4b36a
> change-id: 20230601-zswap-cgroup-wsometimes-uninitialized-b549ff4247ed
>
> Best regards,
> --
> Nathan Chancellor <nathan@kernel.org>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] zswap: Avoid uninitialized use of ret in zswap_frontswap_store()
2023-06-01 18:35 ` Yosry Ahmed
@ 2023-06-01 19:21 ` Nhat Pham
0 siblings, 0 replies; 3+ messages in thread
From: Nhat Pham @ 2023-06-01 19:21 UTC (permalink / raw)
To: Yosry Ahmed
Cc: Nathan Chancellor, akpm, sjenning, ddstreet, vitaly.wool,
ndesaulniers, trix, linux-mm, llvm, patches, kernel test robot
On Thu, Jun 1, 2023 at 11:36 AM Yosry Ahmed <yosryahmed@google.com> wrote:
>
> On Thu, Jun 1, 2023 at 11:34 AM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > Clang warns:
> >
> > mm/zswap.c:1183:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> > 1183 | if (objcg && !obj_cgroup_may_zswap(objcg))
> > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > mm/zswap.c:1327:9: note: uninitialized use occurs here
> > 1327 | return ret;
> > | ^~~
> > mm/zswap.c:1183:2: note: remove the 'if' if its condition is always false
> > 1183 | if (objcg && !obj_cgroup_may_zswap(objcg))
> > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > 1184 | goto reject;
> > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > mm/zswap.c:1158:9: note: initialize the variable 'ret' to silence this warning
> > 1158 | int ret;
> > | ^
> > | = 0
> > 1 error generated.
> >
> > This condition used to return -ENOMEM by going to the shrink label, so
> > set ret to -ENOMEM in the if block explicitly to avoid using it
> > uninitialized.
> >
> > Fixes: 6804144bf1cf ("zswap: do not shrink if cgroup may not zswap")
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/202306011435.2BxsHFUE-lkp@intel.com/
> > Closes: https://lore.kernel.org/202306012152.o4FL7Y6J-lkp@intel.com/
> > Closes: https://github.com/ClangBuiltLinux/linux/issues/1861
> > Signed-off-by: Nathan Chancellor <nathan@kernel.org>
>
> Thanks!
>
> Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
>
> > ---
> > Changes in v2:
> > - Change ret to -ENOMEM to match this condition's previous return value
> > (Yosry)
> > - Link to v1: https://lore.kernel.org/r/20230601-zswap-cgroup-wsometimes-uninitialized-v1-1-35debdd19293@kernel.org
> > ---
> > mm/zswap.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/zswap.c b/mm/zswap.c
> > index cff93643a6ab..30092d9a3b23 100644
> > --- a/mm/zswap.c
> > +++ b/mm/zswap.c
> > @@ -1180,8 +1180,10 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
> > * local cgroup limits.
> > */
> > objcg = get_obj_cgroup_from_page(page);
> > - if (objcg && !obj_cgroup_may_zswap(objcg))
> > + if (objcg && !obj_cgroup_may_zswap(objcg)) {
> > + ret = -ENOMEM;
> > goto reject;
> > + }
> >
> > /* reclaim space if needed */
> > if (zswap_is_full()) {
> >
> > ---
> > base-commit: b2424568bd9b947b2698b693ff24fec63bb4b36a
> > change-id: 20230601-zswap-cgroup-wsometimes-uninitialized-b549ff4247ed
> >
> > Best regards,
> > --
> > Nathan Chancellor <nathan@kernel.org>
> >
Acked-by: Nhat Pham <nphamcs@gmail.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-06-01 18:34 [PATCH v2] zswap: Avoid uninitialized use of ret in zswap_frontswap_store() Nathan Chancellor
2023-06-01 18:35 ` Yosry Ahmed
2023-06-01 19:21 ` Nhat Pham
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