From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 76772CD5BD1 for ; Mon, 1 Jun 2026 14:16:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D9F526B03BF; Mon, 1 Jun 2026 10:16:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D50066B03C1; Mon, 1 Jun 2026 10:16:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C65A66B03C2; Mon, 1 Jun 2026 10:16:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id B76D36B03BF for ; Mon, 1 Jun 2026 10:16:32 -0400 (EDT) Received: from smtpin13.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 2C1751A06C4 for ; Mon, 1 Jun 2026 14:16:32 +0000 (UTC) X-FDA: 84831544224.13.CD40BC0 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf23.hostedemail.com (Postfix) with ESMTP id 6368014000D for ; Mon, 1 Jun 2026 14:16:30 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=CyV1ioMe; spf=pass (imf23.hostedemail.com: domain of pratyush@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=pratyush@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1780323390; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=9VT/rV29GtgCByoYfuOFThPGA055lDO6NINlnaI0eUs=; b=zQ1HVBMrI/xF6kQPJr0ivgXlzG433R/G1MuWNTVP8BFeLOpyp8ofciR/g9Q8u2C7L2910j KNY2XnmQDVYnVbg5LQCn9OiWCWDVqlO7OuMuVDDT/Il4ZLxtwxVCJ4nErPbV8h3lssx1k3 jgvtp9Dr3I/dyYCUantRT/N52eDOTFw= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=CyV1ioMe; spf=pass (imf23.hostedemail.com: domain of pratyush@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=pratyush@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1780323390; a=rsa-sha256; cv=none; b=OZ0qWgZXfE36/SpwOHYVmsvJsC+S1wMzINpw9lpwyX0sB9eRHFdj+C/RShmjka6ssifFJj ZV3WjvWDhgg0RQk9atcslpuQEmwYT4p+kFQr3ll7xSb3htHrR5Xmg6dZzEQtpsruKVlrzV B1xmr8uutzMO1FFMmeCPzstpb2+33lg= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 4E4EE4442C; Mon, 1 Jun 2026 14:16:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C57311F00893; Mon, 1 Jun 2026 14:16:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780323389; bh=9VT/rV29GtgCByoYfuOFThPGA055lDO6NINlnaI0eUs=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=CyV1ioMeC0MrkZO3l5+K8ePNL09lvyi4xXcudGdAXLNG9IPjHzE+0g7eMJPAm6TQX pB4yBliMwXmEYVa/q/5S76gybE+X5As99r8Sb8MB2B5754y6xz2GEwTyCgKq+xWnlr Hz0f5N7FkH1AnxnLOdgG4rnYPHIjHSaicTSORO7MMJUfsezlOUeP0WSvY/El2cvDTN 7WXQpq7XLNwSU4egIBcF6VcBssJyPCsVEAKRfHClh073Snmf+UPzTKiXoR56gHJlF0 aDqNLY0f/vsQfJ4hXxX9BePyRwvH3vysXoo5/h9fQHwdXDbrMTNNVX+T54Pg5AcyNu rZ9ohj2uqhqFQ== From: Pratyush Yadav To: Pasha Tatashin Cc: linux-kselftest@vger.kernel.org, rppt@kernel.org, shuah@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, skhan@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, corbet@lwn.net, dmatlack@google.com, kexec@lists.infradead.org, pratyush@kernel.org, skhawaja@google.com, graf@amazon.com Subject: Re: [PATCH v4 10/13] liveupdate: Remove limit on the number of files per session In-Reply-To: <20260530221938.115978-11-pasha.tatashin@soleen.com> (Pasha Tatashin's message of "Sat, 30 May 2026 22:19:35 +0000") References: <20260530221938.115978-1-pasha.tatashin@soleen.com> <20260530221938.115978-11-pasha.tatashin@soleen.com> Date: Mon, 01 Jun 2026 16:16:25 +0200 Message-ID: <2vxzbjdufirq.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 6368014000D X-Stat-Signature: t538ks58sq539iuh9mqcgmjmmkjmyu9b X-HE-Tag: 1780323390-77268 X-HE-Meta: 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 i2Tv3Lzr DB9yGKKPt9yzIzJoSo4wCfCHkXtNo0noXfYTPm4RyiqzByyWVAu4JK+rmYRWPs36tdUu29DUQ9H/X8SMcX4tDbv6+t2v5KNbMb8HdLs4fNlDXWtaln/WTDfnks0omGWzyBOYP9I/uMGp+XgBMCNRgt8NYmvqqrGizFCJL4nCHC4jdwRNZV0Dko5zIb59Qf/eqvpdGLNR30GhMHnBO7U/sUW8QWHmLBXxCfWsuZnv9gzxupGbKVd3wV5kc08udD88aJrQn Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, May 30 2026, Pasha Tatashin wrote: > To remove the fixed limit on the number of preserved files per session, > transition the file metadata serialization from a single contiguous > memory block to a chain of linked blocks. > > Acked-by: Mike Rapoport (Microsoft) > Signed-off-by: Pasha Tatashin > --- > include/linux/kho/abi/luo.h | 13 +-- > kernel/liveupdate/luo_file.c | 144 +++++++++++++++---------------- > kernel/liveupdate/luo_internal.h | 6 +- > 3 files changed, 80 insertions(+), 83 deletions(-) > > diff --git a/include/linux/kho/abi/luo.h b/include/linux/kho/abi/luo.h > index 79758d92ed5f..16df550ef143 100644 > --- a/include/linux/kho/abi/luo.h > +++ b/include/linux/kho/abi/luo.h > @@ -35,8 +35,8 @@ > * > * - struct luo_session_ser: > * Metadata for a single session, including its name and a physical pointer > - * to another preserved memory block containing an array of > - * `struct luo_file_ser` for all files in that session. > + * to the first `struct kho_block_header_ser` for all files in that session. > + * Multiple blocks are linked via the `next` field in the header. > * > * - struct luo_file_ser: > * Metadata for a single preserved file. Contains the `compatible` string to > @@ -65,7 +65,7 @@ > * The LUO state is registered under this KHO entry name. > */ > #define LUO_KHO_ENTRY_NAME "LUO" > -#define LUO_COMPAT_BASE "luo-v3" > +#define LUO_COMPAT_BASE "luo-v4" > #define LUO_ABI_COMPATIBLE LUO_COMPAT_BASE "-" KHO_BLOCK_ABI_COMPATIBLE > #define LUO_ABI_COMPAT_LEN ALIGN(sizeof(LUO_ABI_COMPATIBLE), 8) > > @@ -103,9 +103,10 @@ struct luo_file_ser { > > /** > * struct luo_file_set_ser - Represents the serialized metadata for file set > - * @files: The physical address of a contiguous memory block that holds > - * the serialized state of files (array of luo_file_ser) in this file > - * set. > + * @files: The physical address of the first `struct kho_block_header_ser`. > + * This structure is the header for a block of memory containing > + * an array of `struct luo_file_ser` entries. Multiple blocks are > + * linked via the `next` field in the header. > * @count: The total number of files that were part of this session during > * serialization. Used for iteration and validation during > * restoration. > diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c > index 9eec07a9e9fc..a445b1950ca7 100644 > --- a/kernel/liveupdate/luo_file.c > +++ b/kernel/liveupdate/luo_file.c > @@ -118,11 +118,6 @@ static LIST_HEAD(luo_file_handler_list); > /* Keep track of files being preserved by LUO */ > static DEFINE_XARRAY(luo_preserved_files); > > -/* 2 4K pages, give space for 128 files per file_set */ > -#define LUO_FILE_PGCNT 2ul > -#define LUO_FILE_MAX \ > - ((LUO_FILE_PGCNT << PAGE_SHIFT) / sizeof(struct luo_file_ser)) > - > /** > * struct luo_file - Represents a single preserved file instance. > * @fh: Pointer to the &struct liveupdate_file_handler that manages > @@ -174,39 +169,6 @@ struct luo_file { > u64 token; > }; > > -static int luo_alloc_files_mem(struct luo_file_set *file_set) > -{ > - size_t size; > - void *mem; > - > - if (file_set->files) > - return 0; > - > - WARN_ON_ONCE(file_set->count); > - > - size = LUO_FILE_PGCNT << PAGE_SHIFT; > - mem = kho_alloc_preserve(size); > - if (IS_ERR(mem)) > - return PTR_ERR(mem); > - > - file_set->files = mem; > - > - return 0; > -} > - > -static void luo_free_files_mem(struct luo_file_set *file_set) > -{ > - /* If file_set has files, no need to free preservation memory */ > - if (file_set->count) > - return; > - > - if (!file_set->files) > - return; > - > - kho_unpreserve_free(file_set->files); > - file_set->files = NULL; > -} > - > static unsigned long luo_get_id(struct liveupdate_file_handler *fh, > struct file *file) > { > @@ -276,16 +238,15 @@ int luo_preserve_file(struct luo_file_set *file_set, u64 token, int fd) > if (luo_token_is_used(file_set, token)) > return -EEXIST; > > - if (file_set->count == LUO_FILE_MAX) > - return -ENOSPC; > + err = kho_block_grow(&file_set->block_set, file_set->count); > + if (err) > + return err; > > file = fget(fd); > - if (!file) > - return -EBADF; > - > - err = luo_alloc_files_mem(file_set); > - if (err) > - goto err_fput; > + if (!file) { > + err = -EBADF; > + goto err_shrink; > + } > > err = -ENOENT; > down_read(&luo_register_rwlock); > @@ -300,7 +261,7 @@ int luo_preserve_file(struct luo_file_set *file_set, u64 token, int fd) > > /* err is still -ENOENT if no handler was found */ > if (err) > - goto err_free_files_mem; > + goto err_fput; > > err = xa_insert(&luo_preserved_files, luo_get_id(fh, file), > file, GFP_KERNEL); > @@ -343,10 +304,10 @@ int luo_preserve_file(struct luo_file_set *file_set, u64 token, int fd) > xa_erase(&luo_preserved_files, luo_get_id(fh, file)); > err_module_put: > module_put(fh->ops->owner); > -err_free_files_mem: > - luo_free_files_mem(file_set); > err_fput: > fput(file); > +err_shrink: > + kho_block_shrink(&file_set->block_set, file_set->count); > > return err; > } > @@ -392,13 +353,14 @@ void luo_file_unpreserve_files(struct luo_file_set *file_set) > > list_del(&luo_file->list); > file_set->count--; > + kho_block_shrink(&file_set->block_set, file_set->count); > > fput(luo_file->file); > mutex_destroy(&luo_file->mutex); > kfree(luo_file); > } > > - luo_free_files_mem(file_set); > + kho_block_destroy(&file_set->block_set); > } > > static int luo_file_freeze_one(struct luo_file_set *file_set, > @@ -454,7 +416,7 @@ static void __luo_file_unfreeze(struct luo_file_set *file_set, > luo_file_unfreeze_one(file_set, luo_file); > } > > - memset(file_set->files, 0, LUO_FILE_PGCNT << PAGE_SHIFT); > + kho_block_set_clear(&file_set->block_set); > } > > /** > @@ -493,19 +455,23 @@ static void __luo_file_unfreeze(struct luo_file_set *file_set, > int luo_file_freeze(struct luo_file_set *file_set, > struct luo_file_set_ser *file_set_ser) > { > - struct luo_file_ser *file_ser = file_set->files; > struct luo_file *luo_file; > + struct kho_block_it it; > int err; > - int i; > > if (!file_set->count) > return 0; > > - if (WARN_ON(!file_ser)) > - return -EINVAL; > + kho_block_it_init(&it, &file_set->block_set); > > - i = 0; > list_for_each_entry(luo_file, &file_set->files_list, list) { > + struct luo_file_ser *file_ser = kho_block_it_next(&it); > + > + if (!file_ser) { > + err = -ENOSPC; > + goto err_unfreeze; > + } This should not fail normally, right? Since we pre-allocate the memory. Perhaps add a comment saying that? > + > err = luo_file_freeze_one(file_set, luo_file); > if (err < 0) { > pr_warn("Freeze failed for token[%#0llx] handler[%s] err[%pe]\n", > @@ -514,16 +480,21 @@ int luo_file_freeze(struct luo_file_set *file_set, > goto err_unfreeze; > } > > - strscpy(file_ser[i].compatible, luo_file->fh->compatible, > - sizeof(file_ser[i].compatible)); > - file_ser[i].data = luo_file->serialized_data; > - file_ser[i].token = luo_file->token; > - i++; > + strscpy(file_ser->compatible, luo_file->fh->compatible, > + sizeof(file_ser->compatible)); > + file_ser->data = luo_file->serialized_data; > + file_ser->token = luo_file->token; > } > + kho_block_it_finalize(&it); > > file_set_ser->count = file_set->count; > - if (file_set->files) > - file_set_ser->files = virt_to_phys(file_set->files); > + if (!list_empty(&file_set->block_set.blocks)) { > + struct kho_block *block; > + > + block = list_first_entry(&file_set->block_set.blocks, > + struct kho_block, list); > + file_set_ser->files = virt_to_phys(block->ser); > + } Please, add an API in KHO block to return the header physical address. Poking into the internals of the data structure like this is not a good idea. I missed that patch 9 also does this. So please use that there too. > > return 0; > > @@ -741,14 +712,12 @@ int luo_file_finish(struct luo_file_set *file_set) > module_put(luo_file->fh->ops->owner); > list_del(&luo_file->list); > file_set->count--; > + kho_block_shrink(&file_set->block_set, file_set->count); > mutex_destroy(&luo_file->mutex); > kfree(luo_file); > } > > - if (file_set->files) { > - kho_restore_free(file_set->files); > - file_set->files = NULL; > - } > + kho_block_destroy(&file_set->block_set); > > return 0; > } > @@ -822,16 +791,18 @@ int luo_file_deserialize(struct luo_file_set *file_set, > struct luo_file_set_ser *file_set_ser) > { > struct luo_file_ser *file_ser; > + struct kho_block_it it; > int err; > - u64 i; > > if (!file_set_ser->files) { > WARN_ON(file_set_ser->count); > return 0; > } > > - file_set->count = file_set_ser->count; > - file_set->files = phys_to_virt(file_set_ser->files); > + file_set->count = 0; > + err = kho_block_restore(&file_set->block_set, file_set_ser->files); > + if (err) > + return err; > > /* > * Note on error handling: > @@ -848,25 +819,50 @@ int luo_file_deserialize(struct luo_file_set *file_set, > * userspace to detect the failure and trigger a reboot, which will > * reliably reset devices and reclaim memory. > */ > - file_ser = file_set->files; > - for (i = 0; i < file_set->count; i++) { > - err = luo_file_deserialize_one(file_set, &file_ser[i]); > + kho_block_it_init(&it, &file_set->block_set); > + while ((file_ser = kho_block_it_read(&it))) { > + err = luo_file_deserialize_one(file_set, file_ser); > if (err) > - return err; > + goto err_destroy_blocks; > + file_set->count++; > + } > + > + if (file_set->count != file_set_ser->count) { > + pr_warn("File count mismatch: expected %llu, found %llu\n", > + file_set_ser->count, file_set->count); > + err = -EINVAL; > + goto err_destroy_blocks; > } > > return 0; > + > +err_destroy_blocks: > + while (!list_empty(&file_set->files_list)) { > + struct luo_file *luo_file; > + > + luo_file = list_first_entry(&file_set->files_list, > + struct luo_file, list); > + list_del(&luo_file->list); > + module_put(luo_file->fh->ops->owner); > + mutex_destroy(&luo_file->mutex); > + kfree(luo_file); > + } > + file_set->count = 0; > + kho_block_destroy(&file_set->block_set); > + return err; > } > > void luo_file_set_init(struct luo_file_set *file_set) > { > INIT_LIST_HEAD(&file_set->files_list); > + kho_block_set_init(&file_set->block_set, sizeof(struct luo_file_ser)); > } > > void luo_file_set_destroy(struct luo_file_set *file_set) > { > WARN_ON(file_set->count); > WARN_ON(!list_empty(&file_set->files_list)); > + WARN_ON(!list_empty(&file_set->block_set.blocks)); Here too. > } > > /** > diff --git a/kernel/liveupdate/luo_internal.h b/kernel/liveupdate/luo_internal.h > index ee18f9a11b91..64879ffe7378 100644 > --- a/kernel/liveupdate/luo_internal.h > +++ b/kernel/liveupdate/luo_internal.h > @@ -10,6 +10,7 @@ > > #include > #include > +#include > > struct luo_ucmd { > void __user *ubuffer; > @@ -44,14 +45,13 @@ static inline int luo_ucmd_respond(struct luo_ucmd *ucmd, > * struct luo_file_set - A set of files that belong to the same sessions. > * @files_list: An ordered list of files associated with this session, it is > * ordered by preservation time. > - * @files: The physically contiguous memory block that holds the serialized > - * state of files. > + * @block_set: The set of serialization blocks. > * @count: A counter tracking the number of files currently stored in the > * @files_list for this session. > */ > struct luo_file_set { > struct list_head files_list; > - struct luo_file_ser *files; > + struct kho_block_set block_set; > u64 count; > }; -- Regards, Pratyush Yadav