Commit 3de705a43a46 for kernel

commit 3de705a43a465fa92a45c0a494ec13bf0bad2642
Author: Arnd Bergmann <arnd@arndb.de>
Date:   Tue Apr 14 08:51:58 2026 +0200

    mm/vmscan: avoid false-positive -Wuninitialized warning

    When the -fsanitize=bounds sanitizer is enabled, gcc-16 sometimes runs
    into a corner case in the read_ctrl_pos() pos function, where it sees
    possible undefined behavior from the 'tier' index overflowing, presumably
    in the case that this was called with a negative tier:

    In function 'get_tier_idx',
        inlined from 'isolate_folios' at mm/vmscan.c:4671:14:
    mm/vmscan.c: In function 'isolate_folios':
    mm/vmscan.c:4645:29: error: 'pv.refaulted' is used uninitialized [-Werror=uninitialized]

    Part of the problem seems to be that read_ctrl_pos() has unusual calling
    conventions since commit 37a260870f2c ("mm/mglru: rework type selection")
    where passing MAX_NR_TIERS makes it accumulate all tiers but passing a
    smaller positive number makes it read a single tier instead.

    Shut up the warning by adding a fake initialization to the two instances
    of this variable that can run into that corner case.

    Link: https://lore.kernel.org/all/CAJHvVcjtFW86o5FoQC8MMEXCHAC0FviggaQsd5EmiCHP+1fBpg@mail.gmail.com/
    Link: https://lore.kernel.org/20260414065206.3236176-1-arnd@kernel.org
    Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    Cc: Axel Rasmussen <axelrasmussen@google.com>
    Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
    Cc: Barry Song <baohua@kernel.org>
    Cc: David Hildenbrand <david@kernel.org>
    Cc: Davidlohr Bueso <dave@stgolabs.net>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Kairui Song <kasong@tencent.com>
    Cc: Koichiro Den <koichiro.den@canonical.com>
    Cc: Lorenzo Stoakes <ljs@kernel.org>
    Cc: Michal Hocko <mhocko@kernel.org>
    Cc: Muchun Song <muchun.song@linux.dev>
    Cc: Qi Zheng <zhengqi.arch@bytedance.com>
    Cc: Shakeel Butt <shakeel.butt@linux.dev>
    Cc: Wei Xu <weixugc@google.com>
    Cc: Yuanchu Xie <yuanchu@google.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5a8c8fcccbfc..bd1b1aa12581 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4760,7 +4760,7 @@ static int scan_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 static int get_tier_idx(struct lruvec *lruvec, int type)
 {
 	int tier;
-	struct ctrl_pos sp, pv;
+	struct ctrl_pos sp, pv = {};

 	/*
 	 * To leave a margin for fluctuations, use a larger gain factor (2:3).
@@ -4779,7 +4779,7 @@ static int get_tier_idx(struct lruvec *lruvec, int type)

 static int get_type_to_scan(struct lruvec *lruvec, int swappiness)
 {
-	struct ctrl_pos sp, pv;
+	struct ctrl_pos sp, pv = {};

 	if (swappiness <= MIN_SWAPPINESS + 1)
 		return LRU_GEN_FILE;