[LTP] [PATCH 0/2] shmctl03 fix on 32bit compat mode

[LTP] [PATCH 0/2] shmctl03 fix on 32bit compat mode

[Petr Vorel]

Hi all,

this is yet another attempt to fix shmctl03 on 32 bit compat mode,
alternative to Wei's suggestion [1]. We should merge one of these.

Code suggested by Andrea, I turn it into 2 commits.
Based on the fact that general code was needed only for shmctl03, adding
extra enums is probably not worth.

Kind regards,
Petr

[1] https://patchwork.kernel.org/project/ltp/list/?series=1156943&state=*

Andrea Cervesato (2):
  tst_assert: Use 'long long' to fix 32bit compat mode truncation
  shmctl03: Fix shmmax clamped to INT_MAX in 32bit compat mode

 lib/tst_assert.c                            | 9 +++++----
 testcases/kernel/syscalls/shmctl/shmctl03.c | 6 +++++-
 2 files changed, 10 insertions(+), 5 deletions(-)

-- 
2.55.0


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[LTP] [PATCH 1/2] tst_assert: Use 'long long' to fix 32bit compat mode truncation

[Petr Vorel]

From: Andrea Cervesato <andrea.cervesato@suse.com>

Using 'long long' in tst_assert_ulong() correctly verifies values on
32bit compat mode truncation.

This fixes failure of shmctl03.c on /proc/sys/kernel/shmall on 32bit
(potentially on other sysfs files).

Reported-by: Wei Gao <wegao@suse.com>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
[ pvorel: separate into its own commit, write the commit message ]
Co-developed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
 lib/tst_assert.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/tst_assert.c b/lib/tst_assert.c
index b68bd5d397..5a4896ac52 100644
--- a/lib/tst_assert.c
+++ b/lib/tst_assert.c
@@ -25,16 +25,17 @@ void tst_assert_int(const char *file, const int lineno, const char *path, int va
 
 void tst_assert_ulong(const char *file, const int lineno, const char *path, unsigned long val)
 {
-	unsigned long sys_val;
+	unsigned long long sys_val;
 
-	safe_file_scanf(file, lineno, NULL, path, "%lu", &sys_val);
+	safe_file_scanf(file, lineno, NULL, path, "%llu", &sys_val);
 
-	if (val == sys_val) {
+	if (val == (unsigned long)sys_val) {
 		tst_res_(file, lineno, TPASS, "%s = %lu", path, val);
 		return;
 	}
 
-	tst_res_(file, lineno, TFAIL, "%s != %lu got %lu", path, val, sys_val);
+	tst_res_(file, lineno, TFAIL, "%s != %lu got %lu",
+		path, val, (unsigned long)sys_val);
 }
 
 void tst_assert_file_int(const char *file, const int lineno, const char *path, const char *prefix, int val)
-- 
2.55.0


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Re: [LTP] tst_assert: Use 'long long' to fix 32bit compat mode truncation

[linuxtestproject.agent]

Hi Andrea,

On Fri, 18 Sep 2026, Andrea Cervesato wrote:
> [PATCH 1/2] tst_assert: Use 'long long' to fix 32bit compat mode truncation

--- [PATCH 1/2] ---

> -	if (val == sys_val) {
> +	if (val == (unsigned long)sys_val) {
>  		tst_res_(file, lineno, TPASS, "%s = %lu", path, val);
>  		return;
>  	}
>  
> -	tst_res_(file, lineno, TFAIL, "%s != %lu got %lu", path, val, sys_val);
> +	tst_res_(file, lineno, TFAIL, "%s != %lu got %lu",
> +		path, val, (unsigned long)sys_val);

Casting sys_val to unsigned long causes false passes on 32-bit systems
whenever sys_val exceeds ULONG_MAX and (sys_val & 0xFFFFFFFF) equals val,
while masking the actual value read in the failure log. Compare
val == sys_val directly and report sys_val with %llu on mismatch;
compat-mode truncation should be handled in test-specific code instead of
altering generic assertion semantics.

Verdict - Needs revision

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Note:

The agent can sometimes produce false positives although often its
findings are genuine. If you find issues with the review, please
comment this email or ignore the suggestions.

Regards,
LTP AI Reviewer

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Re: [LTP] tst_assert: Use 'long long' to fix 32bit compat mode truncation

[Petr Vorel]

Hi all,

> Hi Andrea,

> On Fri, 18 Sep 2026, Andrea Cervesato wrote:
> > [PATCH 1/2] tst_assert: Use 'long long' to fix 32bit compat mode truncation

> --- [PATCH 1/2] ---

> > -	if (val == sys_val) {
> > +	if (val == (unsigned long)sys_val) {
> >  		tst_res_(file, lineno, TPASS, "%s = %lu", path, val);
> >  		return;
> >  	}

> > -	tst_res_(file, lineno, TFAIL, "%s != %lu got %lu", path, val, sys_val);
> > +	tst_res_(file, lineno, TFAIL, "%s != %lu got %lu",
> > +		path, val, (unsigned long)sys_val);

> Casting sys_val to unsigned long causes false passes on 32-bit systems
> whenever sys_val exceeds ULONG_MAX and (sys_val & 0xFFFFFFFF) equals val,
> while masking the actual value read in the failure log. Compare
> val == sys_val directly and report sys_val with %llu on mismatch;
> compat-mode truncation should be handled in test-specific code instead of
> altering generic assertion semantics.

I don't understand why casting is problem when the original code used unsigned
long for sys_val.

-	unsigned long sys_val;
+	unsigned long long sys_val;

=> I would say agent is wrong.

But the suggestion to modify the behavior for all tests due single 32bit mode
failure is something to be considered.

@Li @Cyril WDYT? Is this patchset safe, or we use the one contributed by Wei?
Other option would be to handle everything with custom code in shmctl03.c
(wait for library helper until it's really needed).

Also, if we change tst_assert(), do we want to somehow document in the kerneldoc
that code is ready for 32bit?

Kind regards,
Petr

> Verdict - Needs revision

> ---
> Note:

> The agent can sometimes produce false positives although often its
> findings are genuine. If you find issues with the review, please
> comment this email or ignore the suggestions.

> Regards,
> LTP AI Reviewer

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[LTP] [PATCH 2/2] shmctl03: Fix shmmax clamped to INT_MAX in 32bit compat mode

[Petr Vorel]

From: Andrea Cervesato <andrea.cervesato@suse.com>

Kernel clamped /proc/sys/kernel/shmmax in 32bit compat mode
to INT_MAX due change in kernel v2.6.22 in commit
af7c693f14606 ("Cap shmmax at INT_MAX in compat shminfo").
Reflect that.

Reported-by: Wei Gao <wegao@suse.com>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
[ pvorel: separate into its own commit, write the commit message ]
Co-developed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
 testcases/kernel/syscalls/shmctl/shmctl03.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/testcases/kernel/syscalls/shmctl/shmctl03.c b/testcases/kernel/syscalls/shmctl/shmctl03.c
index 9e1c2f0990..0056f2c4b4 100644
--- a/testcases/kernel/syscalls/shmctl/shmctl03.c
+++ b/testcases/kernel/syscalls/shmctl/shmctl03.c
@@ -30,7 +30,11 @@ static void verify_ipcinfo(void)
 	else
 		tst_res(TPASS, "shmmin = 1");
 
-	TST_ASSERT_ULONG(PATH_KERN_SHMMAX, info.shmmax);
+	if (tst_is_compat_mode() && info.shmmax == INT_MAX)
+		tst_res(TPASS, "shmmax clamped to INT_MAX in compat mode");
+	else
+		TST_ASSERT_ULONG(PATH_KERN_SHMMAX, info.shmmax);
+
 	TST_ASSERT_ULONG(PATH_KERN_SHMMNI, info.shmmni);
 	TST_ASSERT_ULONG(PATH_KERN_SHMALL, info.shmall);
 }
-- 
2.55.0


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Re: [LTP] [PATCH 2/2] shmctl03: Fix shmmax clamped to INT_MAX in 32bit compat mode

[Cyril Hrubis]

Hi!
> Reported-by: Wei Gao <wegao@suse.com>
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
> Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
> [ pvorel: separate into its own commit, write the commit message ]
> Co-developed-by: Petr Vorel <pvorel@suse.cz>
> Signed-off-by: Petr Vorel <pvorel@suse.cz>
> ---
>  testcases/kernel/syscalls/shmctl/shmctl03.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/testcases/kernel/syscalls/shmctl/shmctl03.c b/testcases/kernel/syscalls/shmctl/shmctl03.c
> index 9e1c2f0990..0056f2c4b4 100644
> --- a/testcases/kernel/syscalls/shmctl/shmctl03.c
> +++ b/testcases/kernel/syscalls/shmctl/shmctl03.c
> @@ -30,7 +30,11 @@ static void verify_ipcinfo(void)
>  	else
>  		tst_res(TPASS, "shmmin = 1");
>  
> -	TST_ASSERT_ULONG(PATH_KERN_SHMMAX, info.shmmax);
> +	if (tst_is_compat_mode() && info.shmmax == INT_MAX)
> +		tst_res(TPASS, "shmmax clamped to INT_MAX in compat mode");

This should be turned into PATH_KERN_SHMMAX >= INT_MAX check instead of
printing TPASS blindly.

> +	else
> +		TST_ASSERT_ULONG(PATH_KERN_SHMMAX, info.shmmax);
> +
>  	TST_ASSERT_ULONG(PATH_KERN_SHMMNI, info.shmmni);
>  	TST_ASSERT_ULONG(PATH_KERN_SHMALL, info.shmall);
>  }
> -- 
> 2.55.0
> 

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Re: [LTP] [PATCH 2/2] shmctl03: Fix shmmax clamped to INT_MAX in 32bit compat mode

[Petr Vorel]

> Hi!
> > Reported-by: Wei Gao <wegao@suse.com>
> > Reviewed-by: Petr Vorel <pvorel@suse.cz>
> > Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
> > [ pvorel: separate into its own commit, write the commit message ]
> > Co-developed-by: Petr Vorel <pvorel@suse.cz>
> > Signed-off-by: Petr Vorel <pvorel@suse.cz>
> > ---
> >  testcases/kernel/syscalls/shmctl/shmctl03.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)

> > diff --git a/testcases/kernel/syscalls/shmctl/shmctl03.c b/testcases/kernel/syscalls/shmctl/shmctl03.c
> > index 9e1c2f0990..0056f2c4b4 100644
> > --- a/testcases/kernel/syscalls/shmctl/shmctl03.c
> > +++ b/testcases/kernel/syscalls/shmctl/shmctl03.c
> > @@ -30,7 +30,11 @@ static void verify_ipcinfo(void)
> >  	else
> >  		tst_res(TPASS, "shmmin = 1");

> > -	TST_ASSERT_ULONG(PATH_KERN_SHMMAX, info.shmmax);
> > +	if (tst_is_compat_mode() && info.shmmax == INT_MAX)
> > +		tst_res(TPASS, "shmmax clamped to INT_MAX in compat mode");

> This should be turned into PATH_KERN_SHMMAX >= INT_MAX check instead of
> printing TPASS blindly.

Right, I'll send a patch which check:

	if (tst_is_compat_mode() && info.shmmax == INT_MAX) {
		unsigned long long shmmax;
		SAFE_FILE_SCANF(PATH_KERN_SHMMAX, "%llu", &shmmax);
		TST_EXP_LE_LU(INT_MAX, shmmax);
	} else {
		TST_ASSERT_ULONG(PATH_KERN_SHMMAX, info.shmmax);
	}

Kind regards,
Petr

> > +	else
> > +		TST_ASSERT_ULONG(PATH_KERN_SHMMAX, info.shmmax);
> > +
> >  	TST_ASSERT_ULONG(PATH_KERN_SHMMNI, info.shmmni);
> >  	TST_ASSERT_ULONG(PATH_KERN_SHMALL, info.shmall);
> >  }
> > -- 
> > 2.55.0

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