* + liveupdate-defer-flb-module-refcounting-to-active-sessions.patch added to mm-new branch
@ 2026-03-18 18:05 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2026-03-18 18:05 UTC (permalink / raw)
To: mm-commits, rppt, pratyush, dmatlack, pasha.tatashin, akpm
The patch titled
Subject: liveupdate: defer FLB module refcounting to active sessions
has been added to the -mm mm-new branch. Its filename is
liveupdate-defer-flb-module-refcounting-to-active-sessions.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/liveupdate-defer-flb-module-refcounting-to-active-sessions.patch
This patch will later appear in the mm-new branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews. Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.
The mm-new branch of mm.git is not included in linux-next
If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin@soleen.com>
Subject: liveupdate: defer FLB module refcounting to active sessions
Date: Wed, 18 Mar 2026 10:16:42 -0400
Stop pinning modules indefinitely upon FLB registration. Instead,
dynamically take a module reference when the FLB is actively used in a
session (e.g., during preserve and retrieve) and release it when the
session concludes.
This allows modules providing FLB operations to be cleanly unloaded when
not in active use by the live update orchestrator.
Link: https://lkml.kernel.org/r/20260318141637.1870220-14-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: David Matlack <dmatlack@google.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 | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
--- a/kernel/liveupdate/luo_flb.c~liveupdate-defer-flb-module-refcounting-to-active-sessions
+++ a/kernel/liveupdate/luo_flb.c
@@ -112,10 +112,15 @@ static int luo_flb_file_preserve_one(str
struct liveupdate_flb_op_args args = {0};
int err;
+ if (!try_module_get(flb->ops->owner))
+ return -ENODEV;
+
args.flb = flb;
err = flb->ops->preserve(&args);
- if (err)
+ if (err) {
+ module_put(flb->ops->owner);
return err;
+ }
private->outgoing.data = args.data;
private->outgoing.obj = args.obj;
}
@@ -143,6 +148,7 @@ static void luo_flb_file_unpreserve_one(
private->outgoing.data = 0;
private->outgoing.obj = NULL;
+ module_put(flb->ops->owner);
}
}
}
@@ -178,12 +184,17 @@ static int luo_flb_retrieve_one(struct l
if (!found)
return -ENOENT;
+ if (!try_module_get(flb->ops->owner))
+ return -ENODEV;
+
args.flb = flb;
args.data = private->incoming.data;
err = flb->ops->retrieve(&args);
- if (err)
+ if (err) {
+ module_put(flb->ops->owner);
return err;
+ }
private->incoming.obj = args.obj;
private->incoming.retrieved = true;
@@ -217,6 +228,7 @@ static void luo_flb_file_finish_one(stru
private->incoming.data = 0;
private->incoming.obj = NULL;
private->incoming.finished = true;
+ module_put(flb->ops->owner);
}
}
}
@@ -394,11 +406,6 @@ int liveupdate_register_flb(struct liveu
goto err_resume;
}
- if (!try_module_get(flb->ops->owner)) {
- err = -EAGAIN;
- goto err_resume;
- }
-
list_add_tail(&private->list, &luo_flb_global.list);
luo_flb_global.count++;
}
@@ -474,12 +481,11 @@ int liveupdate_unregister_flb(struct liv
private->users--;
/*
* If this is the last file-handler with which we are registred, remove
- * from the global list, and relese module reference.
+ * from the global list.
*/
if (!private->users) {
list_del_init(&private->list);
luo_flb_global.count--;
- module_put(flb->ops->owner);
}
luo_session_resume();
@@ -506,7 +512,8 @@ err_resume:
*
* Return: 0 on success, or a negative errno on failure. -ENODATA means no
* incoming FLB data, -ENOENT means specific flb not found in the incoming
- * data, and -EOPNOTSUPP when live update is disabled or not configured.
+ * data, -ENODEV if the FLB's module is unloading, and -EOPNOTSUPP when
+ * live update is disabled or not configured.
*/
int liveupdate_flb_get_incoming(struct liveupdate_flb *flb, void **objp)
{
_
Patches currently in -mm which might be from pasha.tatashin@soleen.com are
mm-vmalloc-export-clear_vm_uninitialized_flag.patch
kho-fix-kasan-support-for-restored-vmalloc-regions.patch
liveupdate-protect-file-handler-list-with-rwsem.patch
liveupdate-protect-flb-lists-with-rwsem.patch
liveupdate-remove-file-handler-module-refcounting.patch
liveupdate-defer-flb-module-refcounting-to-active-sessions.patch
liveupdate-remove-luo_session_quiesce.patch
liveupdate-auto-unregister-flbs-on-file-handler-unregistration.patch
liveupdate-remove-liveupdate_test_unregister.patch
liveupdate-make-unregister-functions-return-void.patch
^ permalink raw reply [flat|nested] 2+ messages in thread* + liveupdate-defer-flb-module-refcounting-to-active-sessions.patch added to mm-new branch
@ 2026-03-27 17:22 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2026-03-27 17:22 UTC (permalink / raw)
To: mm-commits, pasha.tatashin, akpm
The patch titled
Subject: liveupdate: defer FLB module refcounting to active sessions
has been added to the -mm mm-new branch. Its filename is
liveupdate-defer-flb-module-refcounting-to-active-sessions.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/liveupdate-defer-flb-module-refcounting-to-active-sessions.patch
This patch will later appear in the mm-new branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews. Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.
The mm-new branch of mm.git is not included in linux-next
If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin@soleen.com>
Subject: liveupdate: defer FLB module refcounting to active sessions
Date: Fri, 27 Mar 2026 03:33:29 +0000
Stop pinning modules indefinitely upon FLB registration. Instead,
dynamically take a module reference when the FLB is actively used in a
session (e.g., during preserve and retrieve) and release it when the
session concludes.
This allows modules providing FLB operations to be cleanly unloaded when
not in active use by the live update orchestrator.
Link: https://lkml.kernel.org/r/20260327033335.696621-6-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
kernel/liveupdate/luo_flb.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
--- a/kernel/liveupdate/luo_flb.c~liveupdate-defer-flb-module-refcounting-to-active-sessions
+++ a/kernel/liveupdate/luo_flb.c
@@ -115,10 +115,15 @@ static int luo_flb_file_preserve_one(str
struct liveupdate_flb_op_args args = {0};
int err;
+ if (!try_module_get(flb->ops->owner))
+ return -ENODEV;
+
args.flb = flb;
err = flb->ops->preserve(&args);
- if (err)
+ if (err) {
+ module_put(flb->ops->owner);
return err;
+ }
private->outgoing.data = args.data;
private->outgoing.obj = args.obj;
}
@@ -146,6 +151,7 @@ static void luo_flb_file_unpreserve_one(
private->outgoing.data = 0;
private->outgoing.obj = NULL;
+ module_put(flb->ops->owner);
}
}
}
@@ -181,12 +187,17 @@ static int luo_flb_retrieve_one(struct l
if (!found)
return -ENOENT;
+ if (!try_module_get(flb->ops->owner))
+ return -ENODEV;
+
args.flb = flb;
args.data = private->incoming.data;
err = flb->ops->retrieve(&args);
- if (err)
+ if (err) {
+ module_put(flb->ops->owner);
return err;
+ }
private->incoming.obj = args.obj;
private->incoming.retrieved = true;
@@ -237,6 +248,7 @@ static void luo_flb_file_finish_one(stru
private->incoming.data = 0;
private->incoming.obj = NULL;
private->incoming.finished = true;
+ module_put(flb->ops->owner);
}
}
}
@@ -412,11 +424,6 @@ int liveupdate_register_flb(struct liveu
goto err_resume;
}
- if (!try_module_get(flb->ops->owner)) {
- err = -EAGAIN;
- goto err_resume;
- }
-
list_add_tail(&private->list, &luo_flb_global.list);
luo_flb_global.count++;
}
@@ -493,12 +500,11 @@ int liveupdate_unregister_flb(struct liv
private->users--;
/*
* If this is the last file-handler with which we are registred, remove
- * from the global list, and relese module reference.
+ * from the global list.
*/
if (!private->users) {
list_del_init(&private->list);
luo_flb_global.count--;
- module_put(flb->ops->owner);
}
up_write(&luo_register_rwlock);
@@ -527,7 +533,8 @@ err_resume:
*
* Return: 0 on success, or a negative errno on failure. -ENODATA means no
* incoming FLB data, -ENOENT means specific flb not found in the incoming
- * data, and -EOPNOTSUPP when live update is disabled or not configured.
+ * data, -ENODEV if the FLB's module is unloading, and -EOPNOTSUPP when
+ * live update is disabled or not configured.
*/
int liveupdate_flb_get_incoming(struct liveupdate_flb *flb, void **objp)
{
_
Patches currently in -mm which might be from pasha.tatashin@soleen.com are
liveupdate-prevent-double-management-of-files.patch
memfd-implement-get_id-for-memfd_luo.patch
selftests-liveupdate-add-test-for-double-preservation.patch
liveupdate-safely-print-untrusted-strings.patch
liveupdate-synchronize-lazy-initialization-of-flb-private-state.patch
liveupdate-protect-file-handler-list-with-rwsem.patch
liveupdate-protect-flb-lists-with-luo_register_rwlock.patch
liveupdate-defer-flb-module-refcounting-to-active-sessions.patch
liveupdate-remove-luo_session_quiesce.patch
liveupdate-auto-unregister-flbs-on-file-handler-unregistration.patch
liveupdate-remove-liveupdate_test_unregister.patch
liveupdate-make-unregister-functions-return-void.patch
liveupdate-defer-file-handler-module-refcounting-to-active-sessions.patch
^ permalink raw reply [flat|nested] 2+ messages in thread
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