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Pratyush Yadav writes: > On Tue, Jun 23 2026, Tarun Sahu wrote: > >> Convert raw serialized_data to KHO serializeable pointer (KHOSER_PTR). >> This series also takes care of resolving the bug with memfd of using >> phys_to_virt before checking the args->serialized_data value. >> >> Signed-off-by: Tarun Sahu >> Acked-by: Mike Rapoport (Microsoft) >> --- >> include/linux/kho/abi/luo.h | 5 +++-- >> include/linux/liveupdate.h | 4 ++-- >> kernel/liveupdate/luo_file.c | 24 ++++++++++++------------ >> mm/memfd_luo.c | 20 +++++++++++--------- >> 4 files changed, 28 insertions(+), 25 deletions(-) >> >> diff --git a/include/linux/kho/abi/luo.h b/include/linux/kho/abi/luo.h >> index 288076de6d4a..d5b3b1c0fec1 100644 >> --- a/include/linux/kho/abi/luo.h >> +++ b/include/linux/kho/abi/luo.h >> @@ -59,6 +59,7 @@ >> >> #include >> #include >> +#include >> #include >> >> /* >> @@ -89,14 +90,14 @@ struct luo_ser { >> /** >> * struct luo_file_ser - Represents the serialized preserves files. >> * @compatible: File handler compatible string. >> - * @data: Private data >> + * @serialized_data: The serialized pointer union for this file > > Nit: "serialized pointer union" makes very little sense once you lose > the context of this patch. The union is an implementation detail. I > think "serialized KHO pointer" makes more sense from documentation > perspective. Ack. > >> * @token: User provided token for this file >> * >> * If this structure is modified, `LUO_ABI_COMPATIBLE` must be updated. >> */ >> struct luo_file_ser { >> char compatible[LIVEUPDATE_HNDL_COMPAT_LENGTH]; >> - u64 data; >> + DECLARE_KHOSER_PTR(serialized_data, void *); >> u64 token; >> } __packed; >> >> diff --git a/include/linux/liveupdate.h b/include/linux/liveupdate.h >> index 88722e5caf02..480d638b7d18 100644 >> --- a/include/linux/liveupdate.h >> +++ b/include/linux/liveupdate.h >> @@ -33,7 +33,7 @@ struct file; >> * @file: The file object. For retrieve: [OUT] The callback sets >> * this to the new file. For other ops: [IN] The caller sets >> * this to the file being operated on. >> - * @serialized_data: The opaque u64 handle, preserve/prepare/freeze may update >> + * @serialized_data: The serialized pointer union, preserve/prepare/freeze may update > > Nit: Same here. > >> * this field. >> * @private_data: Private data for the file used to hold runtime state that >> * is not preserved. Set by the handler's .preserve() >> @@ -47,7 +47,7 @@ struct liveupdate_file_op_args { >> struct liveupdate_file_handler *handler; >> int retrieve_status; >> struct file *file; >> - u64 serialized_data; >> + DECLARE_KHOSER_PTR(serialized_data, void *); >> void *private_data; >> }; >> >> diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c >> index c39f96961a85..aecf19033f95 100644 >> --- a/kernel/liveupdate/luo_file.c >> +++ b/kernel/liveupdate/luo_file.c >> @@ -125,7 +125,7 @@ static DEFINE_XARRAY(luo_preserved_files); >> * @file: Pointer to the kernel's &struct file that is being preserved. >> * This is NULL in the new kernel until the file is successfully >> * retrieved. >> - * @serialized_data: The opaque u64 handle to the serialized state of the file. >> + * @serialized_data: The serialized pointer union to the serialized state of the file. >> * This handle is passed back to the handler's .freeze(), >> * .retrieve(), and .finish() callbacks, allowing it to track >> * and update its serialized state across phases. >> @@ -161,7 +161,7 @@ static DEFINE_XARRAY(luo_preserved_files); >> struct luo_file { >> struct liveupdate_file_handler *fh; >> struct file *file; >> - u64 serialized_data; >> + DECLARE_KHOSER_PTR(serialized_data, void *); >> void *private_data; >> int retrieve_status; >> struct mutex mutex; >> @@ -289,7 +289,7 @@ int luo_preserve_file(struct luo_file_set *file_set, u64 token, int fd) >> if (err) >> goto err_kfree; >> >> - luo_file->serialized_data = args.serialized_data; >> + KHOSER_COPY_PTR(luo_file->serialized_data, args.serialized_data); >> luo_file->private_data = args.private_data; >> list_add_tail(&luo_file->list, &file_set->files_list); >> file_set->count++; >> @@ -342,7 +342,7 @@ void luo_file_unpreserve_files(struct luo_file_set *file_set) >> >> args.handler = luo_file->fh; >> args.file = luo_file->file; >> - args.serialized_data = luo_file->serialized_data; >> + KHOSER_COPY_PTR(args.serialized_data, luo_file->serialized_data); >> args.private_data = luo_file->private_data; >> luo_file->fh->ops->unpreserve(&args); >> luo_flb_file_unpreserve(luo_file->fh); >> @@ -375,12 +375,12 @@ static int luo_file_freeze_one(struct luo_file_set *file_set, >> >> args.handler = luo_file->fh; >> args.file = luo_file->file; >> - args.serialized_data = luo_file->serialized_data; >> + KHOSER_COPY_PTR(args.serialized_data, luo_file->serialized_data); >> args.private_data = luo_file->private_data; >> >> err = luo_file->fh->ops->freeze(&args); >> if (!err) >> - luo_file->serialized_data = args.serialized_data; >> + KHOSER_COPY_PTR(luo_file->serialized_data, args.serialized_data); >> } >> >> return err; >> @@ -396,7 +396,7 @@ static void luo_file_unfreeze_one(struct luo_file_set *file_set, >> >> args.handler = luo_file->fh; >> args.file = luo_file->file; >> - args.serialized_data = luo_file->serialized_data; >> + KHOSER_COPY_PTR(args.serialized_data, luo_file->serialized_data); >> args.private_data = luo_file->private_data; >> >> luo_file->fh->ops->unfreeze(&args); >> @@ -483,7 +483,7 @@ int luo_file_freeze(struct luo_file_set *file_set, >> >> strscpy(file_ser->compatible, luo_file->fh->compatible, >> sizeof(file_ser->compatible)); >> - file_ser->data = luo_file->serialized_data; >> + KHOSER_COPY_PTR(file_ser->serialized_data, luo_file->serialized_data); >> file_ser->token = luo_file->token; >> } >> >> @@ -587,7 +587,7 @@ int luo_retrieve_file(struct luo_file_set *file_set, u64 token, >> } >> >> args.handler = luo_file->fh; >> - args.serialized_data = luo_file->serialized_data; >> + KHOSER_COPY_PTR(args.serialized_data, luo_file->serialized_data); >> err = luo_file->fh->ops->retrieve(&args); >> if (err) { >> /* Keep the error code for later use. */ >> @@ -621,7 +621,7 @@ static int luo_file_can_finish_one(struct luo_file_set *file_set, >> >> args.handler = luo_file->fh; >> args.file = luo_file->file; >> - args.serialized_data = luo_file->serialized_data; >> + KHOSER_COPY_PTR(args.serialized_data, luo_file->serialized_data); >> args.retrieve_status = luo_file->retrieve_status; >> can_finish = luo_file->fh->ops->can_finish(&args); >> } >> @@ -638,7 +638,7 @@ static void luo_file_finish_one(struct luo_file_set *file_set, >> >> args.handler = luo_file->fh; >> args.file = luo_file->file; >> - args.serialized_data = luo_file->serialized_data; >> + KHOSER_COPY_PTR(args.serialized_data, luo_file->serialized_data); >> args.retrieve_status = luo_file->retrieve_status; >> >> luo_file->fh->ops->finish(&args); >> @@ -748,7 +748,7 @@ static int luo_file_deserialize_one(struct luo_file_set *file_set, >> >> luo_file->fh = fh; >> luo_file->file = NULL; >> - luo_file->serialized_data = ser->data; >> + KHOSER_COPY_PTR(luo_file->serialized_data, ser->serialized_data); >> luo_file->token = ser->token; >> mutex_init(&luo_file->mutex); >> list_add_tail(&luo_file->list, &file_set->files_list); >> diff --git a/mm/memfd_luo.c b/mm/memfd_luo.c >> index 10f3983b0060..852b61678229 100644 >> --- a/mm/memfd_luo.c >> +++ b/mm/memfd_luo.c >> @@ -257,6 +257,7 @@ static void memfd_luo_unpreserve_folios(struct kho_vmalloc *kho_vmalloc, >> >> static int memfd_luo_preserve(struct liveupdate_file_op_args *args) >> { >> + DECLARE_KHOSER_PTR(sd, struct memfd_luo_ser *); >> struct inode *inode = file_inode(args->file); >> struct memfd_luo_folio_ser *folios_ser; >> struct memfd_luo_ser *ser; >> @@ -309,7 +310,8 @@ static int memfd_luo_preserve(struct liveupdate_file_op_args *args) >> inode_unlock(inode); >> >> args->private_data = folios_ser; >> - args->serialized_data = virt_to_phys(ser); >> + KHOSER_STORE_PTR(sd, ser); >> + KHOSER_COPY_PTR(args->serialized_data, sd); > > This is awkward. Why do you even need sd? Why not just do > KHOSER_STORE_PTR(args->serialized_data, ser)? KHOSER_COPY_PTR() doesn't > give you any type safety for args->serialized_data anyway, so why the > extra steps? Right, I will remove that, It was needed when I was using TYPE(UN)SAFE calls. > >> >> return 0; >> >> @@ -325,11 +327,10 @@ static int memfd_luo_freeze(struct liveupdate_file_op_args *args) >> { >> struct memfd_luo_ser *ser; >> >> - if (WARN_ON_ONCE(!args->serialized_data)) >> + ser = KHOSER_LOAD_PTR(args->serialized_data); >> + if (WARN_ON_ONCE(!ser)) >> return -EINVAL; >> >> - ser = phys_to_virt(args->serialized_data); >> - >> /* >> * The pos might have changed since prepare. Everything else stays the >> * same. >> @@ -344,14 +345,13 @@ static void memfd_luo_unpreserve(struct liveupdate_file_op_args *args) >> struct inode *inode = file_inode(args->file); >> struct memfd_luo_ser *ser; >> >> - if (WARN_ON_ONCE(!args->serialized_data)) >> + ser = KHOSER_LOAD_PTR(args->serialized_data); >> + if (WARN_ON_ONCE(!ser)) >> return; >> >> inode_lock(inode); >> shmem_freeze(inode, false); >> >> - ser = phys_to_virt(args->serialized_data); >> - >> memfd_luo_unpreserve_folios(&ser->folios, args->private_data, >> ser->nr_folios); >> >> @@ -397,7 +397,8 @@ static void memfd_luo_finish(struct liveupdate_file_op_args *args) >> if (args->retrieve_status) >> return; >> >> - if (!args->serialized_data) >> + ser = KHOSER_LOAD_PTR(args->serialized_data); >> + if (!ser) >> return; >> >> ser = phys_to_virt(args->serialized_data); > > This doesn't compile :-( > > You should always _test_ the changes you make. Compiling them is the > first step. _Running_ them is the second. Both are important. Please do > so in the next version. And for every code changes, no matter how > trivial it seems. You never know if a simple looking change can trigger > bugs. > > You should at least run the LUO selftests and make sure they pass. > Right, My bad. >> @@ -523,7 +524,8 @@ static int memfd_luo_retrieve(struct liveupdate_file_op_args *args) >> struct file *file; >> int err; >> >> - if (!args->serialized_data) >> + ser = KHOSER_LOAD_PTR(args->serialized_data); >> + if (!ser) >> return -EINVAL; >> >> ser = phys_to_virt(args->serialized_data); > > Here too, this doesn't compile. > > -- > Regards, > Pratyush Yadav