Linux kernel memory management?

Question

Will Linux Kernel free kmalloc'ed and not kfree'd in kernel module memory after module release just like it's work with user space apps?

Karmastan · Accepted Answer · 2011-01-18 19:02:37Z

9

The kernel will not do any garbage collection for a module. If the module kmallocs a chunk of memory and doesn't kfree it before the module is unloaded, that chunk will stay allocated and inaccessible until the next reboot.

answered Jan 18, 2011 at 19:02

Karmastan

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2 Comments

mpe Over a year ago

The kernel will not do any garbage collection, and also will not free memory when the module exits. The latter is the key difference to a userspace process, which has all it's memory returned to the system when it exits.

caf Over a year ago

Note that exactly the same thing applies in userspace, if you write a module that is loaded using dlopen().

EmbeddedDeveloper · Accepted Answer · 2019-04-23 21:22:23Z

1

As others said, the kernel will not do any garbage collection for a module but device drivers can use devm_* types of resource allocations (called managed resource allocation functions) and the kernel will do all the required cleanups after there is no more reference to the device.

See here for the commented source code in the kernel source for devm_kmalloc.

answered Apr 23, 2019 at 21:22

EmbeddedDeveloper

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