York Jasper Niebuhr ba42b524a0 mm: init_mlocked_on_free_v3 ... Implements the "init_mlocked_on_free" boot option. When this boot option is enabled, any mlock'ed pages are zeroed on free. If the pages are munlock'ed beforehand, no initialization takes place. This boot option is meant to combat the performance hit of "init_on_free" as reported in commit 6471384af2 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options"). With "init_mlocked_on_free=1" only relevant data is freed while everything else is left untouched by the kernel. Correspondingly, this patch introduces no performance hit for unmapping non-mlock'ed memory. The unmapping overhead for purely mlocked memory was measured to be approximately 13%. Realistically, most systems mlock only a fraction of the total memory so the real-world system overhead should be close to zero. Optimally, userspace programs clear any key material or other confidential memory before exit and munlock the according memory regions. If a program crashes, userspace key managers fail to do this job. Accordingly, no munlock operations are performed so the data is caught and zeroed by the kernel. Should the program not crash, all memory will ideally be munlocked so no overhead is caused. CONFIG_INIT_MLOCKED_ON_FREE_DEFAULT_ON can be set to enable "init_mlocked_on_free" by default. Link: https://lkml.kernel.org/r/20240329145605.149917-1-yjnworkstation@gmail.com Signed-off-by: York Jasper Niebuhr <yjnworkstation@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: York Jasper Niebuhr <yjnworkstation@gmail.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>		2024-04-25 20:56:29 -07:00
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acpi	mm: change inlined allocation helpers to account at the call site	2024-04-25 20:55:59 -07:00
asm-generic	mm: change inlined allocation helpers to account at the call site	2024-04-25 20:55:59 -07:00
clocksource
crypto	mm: change inlined allocation helpers to account at the call site	2024-04-25 20:55:59 -07:00
drm
dt-bindings
keys
kunit
kvm
linux	mm: init_mlocked_on_free_v3	2024-04-25 20:56:29 -07:00
math-emu
media
memory
misc
net	mm: change inlined allocation helpers to account at the call site	2024-04-25 20:55:59 -07:00
pcmcia
ras
rdma	fix missing vmalloc.h includes	2024-04-25 20:55:49 -07:00
rv
scsi
soc
sound
target
trace	dax: use huge_zero_folio	2024-04-25 20:56:20 -07:00
uapi	vhost-vdpa: change ioctl # for VDPA_GET_VRING_SIZE	2024-04-08 04:11:04 -04:00
ufs
vdso
video
xen