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Commit 93278814 authored by Sasha Levin's avatar Sasha Levin Committed by Linus Torvalds
Browse files

mm: fix division by 0 in percpu_pagelist_fraction() 



percpu_pagelist_fraction_sysctl_handler() has only considered -EINVAL as
a possible error from proc_dointvec_minmax().

If any other error is returned, it would proceed to divide by zero since
percpu_pagelist_fraction wasn't getting initialized at any point.  For
example, writing 0 bytes into the proc file would trigger the issue.

Signed-off-by: default avatarSasha Levin <levinsasha928@gmail.com>
Reviewed-by: default avatarMinchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 16fbdce6

mm/page_alloc.c

+2 −2
Original line number Diff line number Diff line
@@ -105,7 +105,7 @@ unsigned long totalreserve_pages __read_mostly; 
 */

unsigned long dirty_balance_reserve __read_mostly;



int percpu_pagelist_fraction;

int percpu_pagelist_fraction = 8;

gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;



#ifdef CONFIG_PM_SLEEP
@@ -5203,7 +5203,7 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write, 
	int ret;



	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);

	if (!write || (ret == -EINVAL))

	if (!write || (ret < 0))

		return ret;

	for_each_populated_zone(zone) {

		for_each_possible_cpu(cpu) {