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mm: huge_memory: refactor enabled_store() with set_global_enabled_mode()

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Refactor enabled_store() to use a new set_global_enabled_mode() helper. 
Introduce a separate enum global_enabled_mode and
global_enabled_mode_strings[], mirroring the anon_enabled_mode pattern
from the previous commit.

A separate enum is necessary because the global THP setting does not
support "inherit", only "always", "madvise", and "never".  Reusing
anon_enabled_mode would leave a NULL gap in the string array, causing
sysfs_match_string() to stop early and fail to match entries after the
gap.

The helper uses the same loop pattern as set_anon_enabled_mode(),
iterating over an array of flag bit positions and using
test_and_set_bit()/test_and_clear_bit() to track whether the state
actually changed.

Link: https://lkml.kernel.org/r/20260317-thp_logs-v7-3-31eb98fa5a8b@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Barry Song <baohua@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Breno Leitao 2026-03-17 08:33:58 -07:00 committed by Andrew Morton
parent 82d9ff648c
commit 35a01d9442
1 changed files with 48 additions and 15 deletions
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63
mm/huge_memory.c
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@ -330,30 +330,63 @@ static const char * const anon_enabled_mode_strings[] = {
[ANON_ENABLED_NEVER] = "never",
};
enum global_enabled_mode {
GLOBAL_ENABLED_ALWAYS = 0,
GLOBAL_ENABLED_MADVISE = 1,
GLOBAL_ENABLED_NEVER = 2,
};
static const char * const global_enabled_mode_strings[] = {
[GLOBAL_ENABLED_ALWAYS] = "always",
[GLOBAL_ENABLED_MADVISE] = "madvise",
[GLOBAL_ENABLED_NEVER] = "never",
};
static bool set_global_enabled_mode(enum global_enabled_mode mode)
{
static const unsigned long thp_flags[] = {
TRANSPARENT_HUGEPAGE_FLAG,
TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
};
enum global_enabled_mode m;
bool changed = false;
for (m = 0; m < ARRAY_SIZE(thp_flags); m++) {
if (m == mode)
changed |= !test_and_set_bit(thp_flags[m],
&transparent_hugepage_flags);
else
changed |= test_and_clear_bit(thp_flags[m],
&transparent_hugepage_flags);
}
return changed;
}
static ssize_t enabled_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
ssize_t ret = count;
int mode;
if (sysfs_streq(buf, "always")) {
clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
} else if (sysfs_streq(buf, "madvise")) {
clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
} else if (sysfs_streq(buf, "never")) {
clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
} else
ret = -EINVAL;
mode = sysfs_match_string(global_enabled_mode_strings, buf);
if (mode < 0)
return -EINVAL;
if (ret > 0) {
if (set_global_enabled_mode(mode)) {
int err = start_stop_khugepaged();
if (err)
ret = err;
return err;
} else {
/*
* Recalculate watermarks even when the mode didn't
* change, as the previous code always called
* start_stop_khugepaged() which does this internally.
*/
set_recommended_min_free_kbytes();
}
return ret;
return count;
}
static struct kobj_attribute enabled_attr = __ATTR_RW(enabled);