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mm/page_owner: add MR_NEVER to enum migrate_reason and use it for last_migrate_reason

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The last_migrate_reason field uses -1 as a sentinel value to mean "no
migration has happened".  Replace the four bare -1 occurrences by adding a
proper MR_NEVER member to enum migrate_reason, defining a corresponding
"never_migrated" string in the MIGRATE_REASON trace macro, and updating
the GDB page_owner script to use MR_NEVER instead of the hardcoded -1 so
that lx-dump-page-owner does not incorrectly report unmigrated pages as
migrated.

No functional change.

Link: https://lore.kernel.org/20260714015117.78351-3-ye.liu@linux.dev
Signed-off-by: Ye Liu <ye.liu@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ye Liu
2026-07-14 09:51:01 +08:00
committed by Andrew Morton
parent 53472eb262
commit 7eeed888c9
4 changed files with 10 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/migrate_mode.h
View File

@@ -25,6 +25,7 @@ enum migrate_reason {
MR_LONGTERM_PIN,
MR_DEMOTION,
MR_DAMON,
MR_NEVER, /* page has never been migrated */
MR_TYPES
};

3
include/trace/events/migrate.h
View File

@@ -23,7 +23,8 @@
EM( MR_CONTIG_RANGE, "contig_range") \
EM( MR_LONGTERM_PIN, "longterm_pin") \
EM( MR_DEMOTION, "demotion") \
EMe(MR_DAMON, "damon")
EM( MR_DAMON, "damon") \
EMe(MR_NEVER, "never_migrated")
/*
* First define the enums in the above macros to be exported to userspace

8
mm/page_owner.c
View File

@@ -339,7 +339,7 @@ noinline void __set_page_owner(struct page *page, unsigned short order,
depot_stack_handle_t handle;
handle = save_stack(gfp_mask);
__update_page_owner_handle(page, handle, order, gfp_mask, -1,
__update_page_owner_handle(page, handle, order, gfp_mask, MR_NEVER,
ts_nsec, current->pid, current->tgid,
current->comm);
inc_stack_record_count(handle, gfp_mask, 1 << order);
@@ -596,7 +596,7 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
if (ret >= count)
goto err;
if (page_owner->last_migrate_reason != -1) {
if (page_owner->last_migrate_reason != MR_NEVER) {
ret += scnprintf(kbuf + ret, count - ret,
"Page has been migrated, last migrate reason: %s\n",
migrate_reason_names[page_owner->last_migrate_reason]);
@@ -667,7 +667,7 @@ void __dump_page_owner(const struct page *page)
stack_depot_print(handle);
}
if (page_owner->last_migrate_reason != -1)
if (page_owner->last_migrate_reason != MR_NEVER)
pr_alert("page has been migrated, last migrate reason: %s\n",
migrate_reason_names[page_owner->last_migrate_reason]);
page_ext_put(page_ext);
@@ -826,7 +826,7 @@ static void init_pages_in_zone(struct zone *zone)
/* Found early allocated page */
__update_page_owner_handle(page, early_handle, 0, 0,
-1, local_clock(), current->pid,
MR_NEVER, local_clock(), current->pid,
current->tgid, current->comm);
count++;
ext_put_continue:

4
scripts/gdb/linux/page_owner.py
View File

@@ -34,6 +34,7 @@ class DumpPageOwner(gdb.Command):
max_pfn = None
p_ops = None
migrate_reason_names = None
mr_never = None
def __init__(self):
super(DumpPageOwner, self).__init__("lx-dump-page-owner", gdb.COMMAND_SUPPORT)
@@ -65,6 +66,7 @@ class DumpPageOwner(gdb.Command):
self.max_pfn = int(gdb.parse_and_eval("max_pfn"))
self.page_ext_size = int(gdb.parse_and_eval("page_ext_size"))
self.migrate_reason_names = gdb.parse_and_eval('migrate_reason_names')
self.mr_never = int(gdb.parse_and_eval('MR_NEVER'))
def page_ext_invalid(self, page_ext):
if page_ext == gdb.Value(0):
@@ -138,7 +140,7 @@ class DumpPageOwner(gdb.Command):
else:
gdb.write('page last free stack trace:\n')
stackdepot.stack_depot_print(page_owner["free_handle"])
if page_owner['last_migrate_reason'] != -1:
if page_owner['last_migrate_reason'] != self.mr_never:
gdb.write('page has been migrated, last migrate reason: %s\n' % self.migrate_reason_names[page_owner['last_migrate_reason']])
def read_page_owner(self):