Subject: + mm-prevent-setting-of-a-value-less-than-0-to-min_free_kbytes.patch added to -mm tree
To: hanpt@xxxxxxxxxxxxxxxxxx,mhocko@xxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 08 Jan 2014 14:23:51 -0800
The patch titled
Subject: mm: prevent setting of a value less than 0 to min_free_kbytes
has been added to the -mm tree. Its filename is
mm-prevent-setting-of-a-value-less-than-0-to-min_free_kbytes.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-prevent-setting-of-a-value-less-than-0-to-min_free_kbytes.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-prevent-setting-of-a-value-less-than-0-to-min_free_kbytes.patch
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From: Han Pingtian <hanpt@xxxxxxxxxxxxxxxxxx>
Subject: mm: prevent setting of a value less than 0 to min_free_kbytes
If echo -1 > /proc/vm/sys/min_free_kbytes, the system will hang. Changing
proc_dointvec() to proc_dointvec_minmax() in the
min_free_kbytes_sysctl_handler() can prevent this to happen.
mhocko said:
: You can still do echo $BIG_VALUE > /proc/vm/sys/min_free_kbytes and make
: your machine unusable but I agree that proc_dointvec_minmax is more
: suitable here as we already have:
:
: .proc_handler = min_free_kbytes_sysctl_handler,
: .extra1 = &zero,
:
: It used to work properly but then 6fce56ec91b5 ("sysctl: Remove references
: to ctl_name and strategy from the generic sysctl table") has removed
: sysctl_intvec strategy and so extra1 is ignored.
Signed-off-by: Han Pingtian <hanpt@xxxxxxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff -puN mm/page_alloc.c~mm-prevent-setting-of-a-value-less-than-0-to-min_free_kbytes mm/page_alloc.c
--- a/mm/page_alloc.c~mm-prevent-setting-of-a-value-less-than-0-to-min_free_kbytes
+++ a/mm/page_alloc.c
@@ -5767,7 +5767,12 @@ module_init(init_per_zone_wmark_min)
int min_free_kbytes_sysctl_handler(ctl_table *table, int write,
void __user *buffer, size_t *length, loff_t *ppos)
{
- proc_dointvec(table, write, buffer, length, ppos);
+ int rc;
+
+ rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
+ if (rc)
+ return rc;
+
if (write) {
user_min_free_kbytes = min_free_kbytes;
setup_per_zone_wmarks();
_
Patches currently in -mm which might be from hanpt@xxxxxxxxxxxxxxxxxx are
mm-prevent-setting-of-a-value-less-than-0-to-min_free_kbytes.patch
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