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mm: huge_memory: use sysfs_match_string() in defrag_store()

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Patch series "mm: huge_memory: clean up defrag sysfs with shared", v2.

Refactor defrag_store() and defrag_show() to use shared data tables
instead of duplicated if/else chains.

Patch 1 introduces an enum defrag_mode, a defrag_mode_strings[] table, and
a defrag_flags[] mapping array, then rewrites defrag_store() to use
sysfs_match_string() with a loop over defrag_flags[].

Patch 2 refactors defrag_show() to use the same arrays, replacing its
hardcoded if/else chain of test_bit() calls and string literals.

This follows the same pattern applied to anon_enabled_store() in commit
522dfb4ba71f ("mm: huge_memory: refactor anon_enabled_store() with
change_anon_orders()").


This patch (of 2):

Replace the if/else chain of sysfs_streq() calls in defrag_store() with
sysfs_match_string() and a defrag_mode_strings[] table.

Introduce enum defrag_mode and defrag_flags[] array mapping each mode to
its corresponding transparent_hugepage_flag.  The store function now loops
over defrag_flags[], setting the bit for the selected mode and clearing
the others.  When mode is DEFRAG_NEVER (index 4), no index in the
4-element defrag_flags[] matches, so all flags are cleared.

Note that the enum ordering (always, defer, defer+madvise, madvise, never)
differs from the original if/else chain order in defrag_store() (always,
defer+madvise, defer, madvise, never).  This is intentional to match the
display order used by defrag_show().

This is a follow-up cleanup to commit 522dfb4ba71f ("mm: huge_memory:
refactor anon_enabled_store() with change_anon_orders()") which applied
the same sysfs_match_string() pattern to anon_enabled_store().

Link: https://lore.kernel.org/20260408-thp_defrag-v2-0-bc544c1bde4e@debian.org
Link: https://lore.kernel.org/20260408-thp_defrag-v2-1-bc544c1bde4e@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Tested-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Tested-by: Zi Yan <ziy@nvidia.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Liam Howlett <liam@infradead.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Breno Leitao 2026-04-08 08:47:00 -07:00 committed by Andrew Morton
parent 98e09ce7bb
commit b0f3d00e15
1 changed files with 34 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
mm/huge_memory.c
View File

@ -429,6 +429,29 @@ ssize_t single_hugepage_flag_store(struct kobject *kobj,
return count;
}
enum defrag_mode {
DEFRAG_ALWAYS = 0,
DEFRAG_DEFER,
DEFRAG_DEFER_MADVISE,
DEFRAG_MADVISE,
DEFRAG_NEVER,
};
static const char * const defrag_mode_strings[] = {
[DEFRAG_ALWAYS] = "always",
[DEFRAG_DEFER] = "defer",
[DEFRAG_DEFER_MADVISE] = "defer+madvise",
[DEFRAG_MADVISE] = "madvise",
[DEFRAG_NEVER] = "never",
};
static const enum transparent_hugepage_flag defrag_flags[] = {
[DEFRAG_ALWAYS] = TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
[DEFRAG_DEFER] = TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
[DEFRAG_DEFER_MADVISE] = TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
[DEFRAG_MADVISE] = TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
};
static ssize_t defrag_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@ -456,34 +479,19 @@ static ssize_t defrag_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
if (sysfs_streq(buf, "always")) {
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
} else if (sysfs_streq(buf, "defer+madvise")) {
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
} else if (sysfs_streq(buf, "defer")) {
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
} else if (sysfs_streq(buf, "madvise")) {
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
} else if (sysfs_streq(buf, "never")) {
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
} else
int mode, m;
mode = sysfs_match_string(defrag_mode_strings, buf);
if (mode < 0)
return -EINVAL;
for (m = 0; m < ARRAY_SIZE(defrag_flags); m++) {
if (m == mode)
set_bit(defrag_flags[m], &transparent_hugepage_flags);
else
clear_bit(defrag_flags[m], &transparent_hugepage_flags);
}
return count;
}
static struct kobj_attribute defrag_attr = __ATTR_RW(defrag);