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Tue, 24 Mar 2026 17:30:50 -0400 (EDT) From: Oskar Gerlicz Kowalczuk To: Pasha Tatashin , Mike Rapoport , Baoquan He Cc: Pratyush Yadav , Andrew Morton , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, Oskar Gerlicz Kowalczuk Subject: [PATCH v4 2/5] kexec: abort liveupdate handover on kernel_kexec() unwind Date: Tue, 24 Mar 2026 22:27:27 +0100 Message-ID: <20260324212730.65290-3-oskar@gerlicz.space> In-Reply-To: <20260324212730.65290-2-oskar@gerlicz.space> References: <20260324212730.65290-1-oskar@gerlicz.space> <20260324212730.65290-2-oskar@gerlicz.space> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 622C88000E X-Stat-Signature: qqfzfj3dnim83cu9zxfz5otmdy8q9myn X-HE-Tag: 1774388022-80037 X-HE-Meta: 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 vbboI3DH Zc1Mk/hi8KVwrArpMYoA9pNDF+zpsa473upfQT0zj+Y8h6iZbBzQIONOFQktltqV/vpD+MoHX/CVCDHrGdFPMUTDio+J26Rc/ZydhHr5LLda7frIQhkxaBDYMaoyFuj9xHktRZGtYepEM8UUGcFAW7oDDUvZ9R19JSPb8I4bRpGneXSr2Z7Em68GfmOY9ak/dhH+YrDqmI6HCIQlW815DLGhmcMTazn0lwBMS3ctmNTt5D5rKDfrxhAx1zVU9JkZp2Zbwehs6bAoREe9yBgbkklk4GJZETKKIQGp1Z5FjW0N8EL8lzHmmYyUYwGSyQg/LSSh+uONaT+NWSuVGEYINtXjhyAZJWkAiu9Qt857Q72k2hm3VktmNpeal1BK0jOUER/q0ZQbNF4ZUXxG59I008Eebsp9mP19FYHsDeLDJgstCXuMyZ5LCF0qiaHRLGCwfmeCX3HVy6V+vIJqXifMqbnsOaaeJt3mNKpQ/ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: liveupdate_reboot() can freeze outgoing session state before the kexec transition completes. v2 only unwound that state when kernel_kexec() returned a non-zero error, which misses the preserve_context path where machine_kexec() can return to the old kernel with error == 0. If that return path skips the abort, outgoing sessions remain stuck in the reboot state and later user space operations cannot make progress. Treat every return to the original kernel after a prepared liveupdate handover as an unwind point and call liveupdate_reboot_abort() there as well. Fixes: 8b32d3ced269 ("kexec: abort liveupdate handover on kernel_kexec() unwind") Signed-off-by: Oskar Gerlicz Kowalczuk --- include/linux/liveupdate.h | 5 +++++ kernel/kexec_core.c | 6 +++++- kernel/liveupdate/luo_core.c | 11 ++++++++++- kernel/liveupdate/luo_internal.h | 1 + kernel/liveupdate/luo_session.c | 30 ++++++++++++++++++++++++++++++ 5 files changed, 51 insertions(+), 2 deletions(-) diff --git a/include/linux/liveupdate.h b/include/linux/liveupdate.h index dd11fdc76a5f..d93b043a0421 100644 --- a/include/linux/liveupdate.h +++ b/include/linux/liveupdate.h @@ -226,6 +226,7 @@ bool liveupdate_enabled(void); /* Called during kexec to tell LUO that entered into reboot */ int liveupdate_reboot(void); +void liveupdate_reboot_abort(void); int liveupdate_register_file_handler(struct liveupdate_file_handler *fh); int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh); @@ -250,6 +251,10 @@ static inline int liveupdate_reboot(void) return 0; } +static inline void liveupdate_reboot_abort(void) +{ +} + static inline int liveupdate_register_file_handler(struct liveupdate_file_handler *fh) { return -EOPNOTSUPP; diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 2fea396d29b9..95710a7d5e56 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -1139,6 +1139,7 @@ bool kexec_load_permitted(int kexec_image_type) int kernel_kexec(void) { int error = 0; + bool liveupdate_prepared = false; if (!kexec_trylock()) return -EBUSY; @@ -1147,6 +1148,7 @@ int kernel_kexec(void) goto Unlock; } + liveupdate_prepared = true; error = liveupdate_reboot(); if (error) goto Unlock; @@ -1230,7 +1232,9 @@ int kernel_kexec(void) } #endif - Unlock: +Unlock: + if (liveupdate_prepared) + liveupdate_reboot_abort(); kexec_unlock(); return error; } diff --git a/kernel/liveupdate/luo_core.c b/kernel/liveupdate/luo_core.c index dda7bb57d421..95a0b81ce60d 100644 --- a/kernel/liveupdate/luo_core.c +++ b/kernel/liveupdate/luo_core.c @@ -233,8 +233,9 @@ int liveupdate_reboot(void) err = kho_finalize(); if (err) { pr_err("kho_finalize failed %d\n", err); + liveupdate_reboot_abort(); /* - * kho_finalize() may return libfdt errors, to aboid passing to + * kho_finalize() may return libfdt errors, to avoid passing to * userspace unknown errors, change this to EAGAIN. */ err = -EAGAIN; @@ -243,6 +244,14 @@ int liveupdate_reboot(void) return err; } +void liveupdate_reboot_abort(void) +{ + if (!liveupdate_enabled()) + return; + + luo_session_abort_reboot(); +} + /** * liveupdate_enabled - Check if the live update feature is enabled. * diff --git a/kernel/liveupdate/luo_internal.h b/kernel/liveupdate/luo_internal.h index e29e1a46b491..d6e9e85004b0 100644 --- a/kernel/liveupdate/luo_internal.h +++ b/kernel/liveupdate/luo_internal.h @@ -87,6 +87,7 @@ int luo_session_retrieve(const char *name, struct file **filep); int __init luo_session_setup_outgoing(void *fdt); int __init luo_session_setup_incoming(void *fdt); int luo_session_serialize(void); +void luo_session_abort_reboot(void); int luo_session_deserialize(void); bool luo_session_quiesce(void); void luo_session_resume(void); diff --git a/kernel/liveupdate/luo_session.c b/kernel/liveupdate/luo_session.c index 63aee9cc881d..cc03fc2bef97 100644 --- a/kernel/liveupdate/luo_session.c +++ b/kernel/liveupdate/luo_session.c @@ -294,6 +294,13 @@ static int luo_session_finish_retrieved(struct luo_session *session) return luo_file_finish(&session->file_set); } +static void luo_session_unfreeze_one(struct luo_session *session, + struct luo_session_ser *ser) +{ + guard(mutex)(&session->mutex); + luo_file_unfreeze(&session->file_set, &ser->file_set_ser); +} + static int luo_session_release(struct inode *inodep, struct file *filep) { struct luo_session *session = filep->private_data; @@ -797,6 +804,29 @@ int luo_session_serialize(void) goto out_put_sessions; } +void luo_session_abort_reboot(void) +{ + struct luo_session_header *sh = &luo_session_global.outgoing; + struct luo_session *session; + int i = 0; + + guard(rwsem_write)(&sh->rwsem); + if (!READ_ONCE(sh->rebooting)) + return; + + list_for_each_entry(session, &sh->list, list) { + if (i >= sh->header_ser->count) + break; + + luo_session_unfreeze_one(session, &sh->ser[i]); + memset(&sh->ser[i], 0, sizeof(sh->ser[i])); + i++; + } + + sh->header_ser->count = 0; + luo_session_reboot_done(sh); +} + /** * luo_session_quiesce - Ensure no active sessions exist and lock session lists. * -- 2.53.0