From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0A7332264C0 for ; Tue, 23 Jun 2026 12:54:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782219260; cv=none; b=fkEBXRX0bk70vHi3IDih/4CLceKT0QSHSaluw9UOlew0Ov/6WI7nSpU/s3+EuPPqy77nEuaXm3k/gtm/0Y9eSlCRj67V5QT7iDaDu05Egz4PPu0NSC8bPxzqJBsfRI6qoOAxV1yCymSF/P6QUFQmxjlV7J0XooDGaBmPqy5gA0w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782219260; c=relaxed/simple; bh=5kZSiUISzeahSGK4CZ3JCydG1y2mjvzQIOVF1W9mew0=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=f7lBnvG2goQji488xvbwwIJYQlAINwMkz/ou6Io++5lG7Xd5s7YKdToSNx614hEaMWYFxa/9rYZa6Bxvg7Km0nSUNJeLn+HCOHYT+wsE4L8bGW1+3UONELfJRs5mIm0kKDwCFrweY96HFftTNu0B1zRlRuQTg1efNbMqUtAaVXo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=auscPAgc; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="auscPAgc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 439211F000E9; Tue, 23 Jun 2026 12:54:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782219258; bh=DXBdTWEwdhn+XOGPfidzRwDwRildye8jC/CmG5OoRC4=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=auscPAgcP/a+TQKaO7yckWkiM0hPzFSYepvdf8kaGBpKfFgU6BZxcXsRxyczANj1b K2O710KVT/ySlT5R2/38DIjHT5rO1FIPxdRCMHqiobjg/9SxhSFi/4oQefDaJLnL2E AqdqzFl0N9QvKcC8DTSgszeKIvSTZxY8t3pPiJ1lkmYPeiFhsqzkZMDidXGeRWg4J/ jKSrQRkZORvk4m88ku5OcqjtpiMQHL0G2X7WVUf77XfEdbK2PzaTaoJHgpZg3LZwO5 12t9IeK1wXUG4z7YbLsrMgn2R4HA7tm1RlUNOhNR3qLtedXXadOYShsz9nK7DOivaN CC8Qji6pgmnRA== From: Pratyush Yadav To: Tarun Sahu Cc: Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Andrew Morton , Alexander Graf , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 3/3] luo: Update serialized data to use KHOSER_PTR In-Reply-To: <20260623105201.3724592-4-tarunsahu@google.com> (Tarun Sahu's message of "Tue, 23 Jun 2026 10:52:01 +0000") References: <20260623105201.3724592-1-tarunsahu@google.com> <20260623105201.3724592-4-tarunsahu@google.com> Date: Tue, 23 Jun 2026 14:54:15 +0200 Message-ID: <2vxztsqtmn7s.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain 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. > * @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? > > 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. > @@ -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