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mm/mempolicy: Ignore runtime policy changes when set through cmdline #6740

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Merged
pelwell merged 1 commit into from
Mar 26, 2025
Merged

mm/mempolicy: Ignore runtime policy changes when set through cmdline #6740

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11 changes: 11 additions & 0 deletions mm/mempolicy.c
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,7 @@
#include <linux/highmem.h>
#include <linux/hugetlb.h>
#include <linux/kernel.h>
#include <linux/ktime.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/sched/numa_balancing.h>
Expand Down Expand Up @@ -138,6 +139,7 @@ static struct mempolicy default_policy = {
.refcnt = ATOMIC_INIT(1), /* never free it */
.mode = MPOL_LOCAL,
};
static bool mempolicy_cmdline_set;

static struct mempolicy preferred_node_policy[MAX_NUMNODES];

Expand Down Expand Up @@ -1629,6 +1631,14 @@ static long kernel_set_mempolicy(int mode, const unsigned long __user *nmask,
int err;

err = sanitize_mpol_flags(&lmode, &mode_flags);

if (mempolicy_cmdline_set) {
// ignore messages during boot which are expected
if (ktime_get_boottime_seconds() > 40)
pr_info("Request to set policy to %d ignored\n", mode);
return 0;
}

if (err)
return err;

Expand Down Expand Up @@ -3402,6 +3412,7 @@ static int __init setup_numapolicy(char *str)
default_policy = pol;
mpol_to_str(buf, sizeof(buf), &pol);
pr_info("NUMA default policy overridden to '%s'\n", buf);
mempolicy_cmdline_set = pol.mode != MPOL_DEFAULT;
} else {
pr_warn("Unable to parse numa_policy=\n");
}
Expand Down