Re: [PATCH] lockdep: Fix static memory detection even more

* Guenter Roeck [off-list ref]:

On 9/3/23 14:11, Helge Deller wrote:

quoted

* Guenter Roeck [off-list ref]:

quoted

Hi,

On Sat, Aug 12, 2023 at 05:48:52PM +0200, Helge Deller wrote:

quoted

On the parisc architecture, lockdep reports for all static objects which
are in the __initdata section (e.g. "setup_done" in devtmpfs,
"kthreadd_done" in init/main.c) this warning:

	INFO: trying to register non-static key.

The warning itself is wrong, because those objects are in the __initdata
section, but the section itself is on parisc outside of range from
_stext to _end, which is why the static_obj() functions returns a wrong
answer.

While fixing this issue, I noticed that the whole existing check can
be simplified a lot.
Instead of checking against the _stext and _end symbols (which include
code areas too) just check for the .data and .bss segments (since we check a
data object). This can be done with the existing is_kernel_core_data()
macro.

In addition objects in the __initdata section can be checked with
init_section_contains().

This partly reverts and simplifies commit bac59d18c701 ("x86/setup: Fix static
memory detection").

Tested on x86-64 and parisc.

Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: bac59d18c701 ("x86/setup: Fix static memory detection")

On loongarch, this patch results in the following backtrace.

EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path
EFI stub: Exiting boot services
[    0.000000] INFO: trying to register non-static key.
[    0.000000] The code is fine but needs lockdep annotation, or maybe
[    0.000000] you didn't initialize this object before use?
[    0.000000] turning off the locking correctness validator.
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0+ #1
[    0.000000] Stack : 0000000000000000 0000000000000000 9000000000223d6c 9000000001df0000
[    0.000000]         9000000001df39a0 9000000001df39a8 0000000000000000 0000000000000000
[    0.000000]         9000000001df39a8 0000000000000001 0000000000000000 900000000154b910
[    0.000000]         fffffffffffffffe 9000000001df39a8 0000000000000000 0000000000000000
[    0.000000]         0000000000000001 0000000000000003 0000000000000010 0000000000000030
[    0.000000]         0000000000000063 0000000000000001 0000000000000000 0000000000000000
[    0.000000]         0000000000000000 0000000000000000 9000000001c60650 9000000001e12000
[    0.000000]         0000000000000000 9000000001560bc0 0000000000000000 9000000002ee6000
[    0.000000]         0000000000000000 0000000000000000 9000000000223d84 0000000000000000
[    0.000000]         00000000000000b0 0000000000000004 0000000000000000 0000000000000800
[    0.000000]         ...
[    0.000000] Call Trace:
[    0.000000] [<9000000000223d84>] show_stack+0x5c/0x180
[    0.000000] [<900000000153e0b4>] dump_stack_lvl+0x88/0xd0
[    0.000000] [<90000000002bc548>] register_lock_class+0x768/0x770
[    0.000000] [<90000000002bc710>] __lock_acquire+0xb0/0x2a18
[    0.000000] [<90000000002bba1c>] lock_acquire+0x11c/0x328
[    0.000000] [<9000000000b34a60>] __debug_object_init+0x60/0x244
[    0.000000] [<9000000000337f94>] init_cgroup_housekeeping+0xe8/0x144
[    0.000000] [<900000000033e364>] init_cgroup_root+0x38/0xa0
[    0.000000] [<90000000017801ac>] cgroup_init_early+0x44/0x16c
[    0.000000] [<9000000001770758>] start_kernel+0x50/0x624
[    0.000000] [<90000000015410b4>] kernel_entry+0xb4/0xc4

Reverting it fixes the problem. Bisect log attached.

This is also seen in v6.5.y and v6.4.y since the patch has been applied
to those branches.

Does this happens with CONFIG_SMP=n ?
If so, I think the untested patch below might fix the issue.

No, this is loongarch:defconfig with various debug options enabled.
That has CONFIG_SMP=y.

Could you apply below patch and verify with the contents of the
System.map file where the lock is located ?

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index e85b5ad3e206..db0a301f9740 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c

@@ -969,7 +969,7 @@ static bool assign_lock_key(struct lockdep_map *lock)
 	else {
 		/* Debug-check: all keys must be persistent! */
 		debug_locks_off();
-		pr_err("INFO: trying to register non-static key.\n");
+		pr_err("INFO: trying to register non-static key at %08lx.\n", addr);
 		pr_err("The code is fine but needs lockdep annotation, or maybe\n");
 		pr_err("you didn't initialize this object before use?\n");
 		pr_err("turning off the locking correctness validator.\n");