From: Rasmus Villemoes Date: Tue, 1 Dec 2015 20:44:50 +0000 (+0100) Subject: x86/mm/mtrr: Mark the 'range_new' static variable in mtrr_calc_range_state() as __ini... X-Git-Tag: v4.5-rc1~162^2~8 X-Git-Url: http://git.cascardo.info/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=c332813b51cbe807d539bb059b81235abf1e3fdd x86/mm/mtrr: Mark the 'range_new' static variable in mtrr_calc_range_state() as __initdata 'range_new' doesn't seem to be used after init. It is only passed to memset(), sum_ranges(), memcmp() and x86_get_mtrr_mem_range(), the latter of which also only passes it on to various *range* library functions. So mark it __initdata to free up an extra page after init. Its contents are wiped at every call to mtrr_calc_range_state(), so it being static is not about preserving state between calls, but simply to avoid a 4k+ stack frame. While there, add a comment explaining this and why it's safe. We could also mark nr_range_new as __initdata, but since it's just a single int and also doesn't carry state between calls (it is unconditionally assigned to before it is read), we might as well make it an ordinary automatic variable. Signed-off-by: Rasmus Villemoes Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Toshi Kani Link: http://lkml.kernel.org/r/1449002691-20783-1-git-send-email-linux@rasmusvillemoes.dk Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/cpu/mtrr/cleanup.c b/arch/x86/kernel/cpu/mtrr/cleanup.c index 70d7c93f4550..0d98503c2245 100644 --- a/arch/x86/kernel/cpu/mtrr/cleanup.c +++ b/arch/x86/kernel/cpu/mtrr/cleanup.c @@ -593,9 +593,16 @@ mtrr_calc_range_state(u64 chunk_size, u64 gran_size, unsigned long x_remove_base, unsigned long x_remove_size, int i) { - static struct range range_new[RANGE_NUM]; + /* + * range_new should really be an automatic variable, but + * putting 4096 bytes on the stack is frowned upon, to put it + * mildly. It is safe to make it a static __initdata variable, + * since mtrr_calc_range_state is only called during init and + * there's no way it will call itself recursively. + */ + static struct range range_new[RANGE_NUM] __initdata; unsigned long range_sums_new; - static int nr_range_new; + int nr_range_new; int num_reg; /* Convert ranges to var ranges state: */