Warn about dangers of LVM/RAID stacking with 4KSTACKS
PATCH 1/1 Warn about dangers of LVM/RAID stacking with 4KSTACKS
Hello Linus
On x86 using software RAID on disks and then putting them together in LVM as a logical volume uses alot of the stack. I've read reports of doing this on volumes which are shared via NFS causes stack overruns which it indeed does, I just reproduced it here.
We should play it safe and warn anyone before using CONFIG_4KSTACKS if the user intends to do software LVM/RAID stacking until this issue is resolved.
Signed-off-by Alexander Nyberg <[email protected]>
===== arch/i386/Kconfig.debug 1.4 vs edited =====
arch/i386/Kconfig.debug +6 -0
@@ -46,6 +46,8 @@ config DEBUG_PAGEALLOC This results in a large slowdown, but helps to find certain types of memory corruptions. +comment "Please read help if you intend to stack software RAID and LVM" + config 4KSTACKS bool "Use 4Kb for kernel stacks instead of 8Kb" help
@@ -54,6 +56,10 @@ config 4KSTACKS running more threads on a system and also reduces the pressure on the VM subsystem for higher order allocations. This option will also use IRQ stacks to compensate for the reduced stackspace. + + Don't enable this if you intend to stack RAID and LVM on top of + each other. The stack may run out using this combination and + then bad things will happen. config X86_FIND_SMP_CONFIG bool