https://bugs.kde.org/show_bug.cgi?id=522300
Bug ID: 522300
Summary: Plasma 6.7.x causes massive kmalloc-128 kernel slab
leak on NVIDIA Wayland
Classification: I don't know
Product: kde
Version First unspecified
Reported In:
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
DESCRIPTION
After logging into a Wayland session, SUnreclaim is immediately ~1.5-6GB,
dominated entirely by kmalloc-128 (tens of millions of objects). Amount varies
between boots (1.5GiB to 6GiB observed). Does not appear to grow significantly
during the session but baseline is already massively elevated compared to
Plasma 6.6.5.
STEPS TO REPRODUCE
1. Boot Arch Linux with Plasma 6.7.1 Wayland session, NVIDIA proprietary driver
580.159.04, GTX 1060
2. Login
3. Run cat /proc/meminfo | grep SUnreclaim and sudo slabtop -o -s c | grep
kmalloc-128
OBSERVED RESULT
SUnreclaim grows to 1.5–6GiB immediately, entirely dominated by kmalloc-128 (up
to 46 million leaked objects).
EXPECTED RESULT
SUnreclaim ~100MB, as observed with Plasma 6.6.5 on identical hardware/drivers.
SOFTWARE/OS VERSIONS
Operating System (available in the Info Center app, or by running `kinfo` in a
terminal window): Arch Linux kernel 7.0.13-arch1-2
KDE Plasma Version: 6.7.1
KDE Frameworks Version: 6.27.0
Qt Version: 6.11.1
GPU: NVIDIA GTX 1060, driver 580.159.04, Wayland
ADDITIONAL INFORMATION
The kmalloc-128 count varies significantly between reboots (observed 11M, 23M,
and 46M objects across different boots).
Blacklisting the NVIDIA proprietary driver (system falls back to llvmpipe)
results in normal SUnreclaim levels (matching Plasma 6.6.5 behavior).
Stats with Plasma 6.7.1 + NVIDIA driver (580.159.04), immediately after login:
sudo slabtop -o -s c | head -n 10
Active / Total Objects (% used) : 46860417 / 46871221 (100.0%)
Active / Total Slabs (% used) : 1464036 / 1464036 (100.0%)
Active / Total Caches (% used) : 149 / 230 (64.8%)
Active / Total Size (% used) : 5982571 / 5984877 (100.0%)
Minimum / Average / Maximum Object : 0.01K / 0.13K / 17.41K
OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
46140832 46140812 99% 0.12K 1441901 32 5767604 kmalloc-128
92204 92196 99% 1.11K 3293 28 105376 ext4_inode_cache
119406 119400 99% 0.19K 5686 21 22744 dentry
cat /proc/meminfo | grep -iE 'slab|sreclaimable|sunreclaim'
Slab: 6021472 kB
SReclaimable: 155384 kB
SUnreclaim: 5866088 kB
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