+ liveupdate-initialize-incoming-flb-state-before-finish.patch added to mm-hotfixes-unstable branch

+ liveupdate-initialize-incoming-flb-state-before-finish.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: liveupdate: initialize incoming FLB state before finish
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     liveupdate-initialize-incoming-flb-state-before-finish.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/liveupdate-initialize-incoming-flb-state-before-finish.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Leo Timmins <leotimmins1974@gmail.com>
Subject: liveupdate: initialize incoming FLB state before finish
Date: Wed, 25 Mar 2026 12:46:08 +0800

luo_flb_file_finish_one() decremented incoming.count before making sure
that the incoming FLB state had been materialized.  If no earlier incoming
retrieval had populated that state, the first decrement ran from zero and
skipped the last-user finish path.

Initialize the incoming FLB state before the first decrement so finish
uses the serialized refcount instead of an uninitialized value.

Link: https://lkml.kernel.org/r/20260325044608.8407-3-leotimmins1974@gmail.com
Fixes: cab056f2aae7 ("liveupdate: luo_flb: introduce File-Lifecycle-Bound global state")
Signed-off-by: Leo Timmins <leotimmins1974@gmail.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/liveupdate/luo_flb.c |   19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

--- a/kernel/liveupdate/luo_flb.c~liveupdate-initialize-incoming-flb-state-before-finish
+++ a/kernel/liveupdate/luo_flb.c
@@ -192,10 +192,27 @@ static int luo_flb_retrieve_one(struct l
 static void luo_flb_file_finish_one(struct liveupdate_flb *flb)
 {
 	struct luo_flb_private *private = luo_flb_get_private(flb);
+	bool needs_retrieve = false;
 	u64 count;
 
-	scoped_guard(mutex, &private->incoming.lock)
+	scoped_guard(mutex, &private->incoming.lock) {
+		if (!private->incoming.count && !private->incoming.finished)
+			needs_retrieve = true;
+	}
+
+	if (needs_retrieve) {
+		int err = luo_flb_retrieve_one(flb);
+
+		if (err) {
+			pr_warn("Failed to retrieve FLB '%s' during finish: %pe\n",
+				flb->compatible, ERR_PTR(err));
+			return;
+		}
+	}
+
+	scoped_guard(mutex, &private->incoming.lock) {
 		count = --private->incoming.count;
+	}
 
 	if (!count) {
 		struct liveupdate_flb_op_args args = {0};
_

Patches currently in -mm which might be from leotimmins1974@gmail.com are

liveupdate-propagate-file-deserialization-failures.patch
liveupdate-initialize-incoming-flb-state-before-finish.patch