From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B25961C2AA for ; Sat, 18 Apr 2026 07:52:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776498738; cv=none; b=LphKGe0rDWQOWNXTD/iHf6dTaXJoBBUnmEnJ38wAiVEM+8Xz6BMOzJc0ZIgFjNZ08f7XfWOYBaUaviExbgweAOFiIodscUolMlLKeykr0P2vs9BWKz9DMwf9qlhsYN8Cq0tpxqbAYqOT3ELuB7gC6UVTQMRCE4LQtc4wfw6KBq4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776498738; c=relaxed/simple; bh=vYLW12hcf0CW6nAqGpA8hmgXAic9pwCMRHK08KMo1bI=; h=Date:To:From:Subject:Message-Id; b=QDwsDk8NdLvllxM5YbM7lHtFw1Bfi9lhT5q8c8rh77BTqNp/tFeknhmvCp6H8fuKh9CREW6Ys4+ZyVjlI8SHi/4aU52XFdnp2lVEXtBl7HVOBxRsTROfh96BNQrFihNcp6eNUpSOQzFp4ShV4KAyf53kjuzcbeSWyf0B3FNa0Aw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=R9I8BzMQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="R9I8BzMQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4BBA2C19424; Sat, 18 Apr 2026 07:52:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1776498738; bh=vYLW12hcf0CW6nAqGpA8hmgXAic9pwCMRHK08KMo1bI=; h=Date:To:From:Subject:From; b=R9I8BzMQUmR3aUv5BEG92f/HJff42gayNe7Lbm2wGR/+ApPZI2xPh9QVJOJ/4MNcg IJw/mqnt4i3SU2/WDPYDRymf9limdCgVgwlo5Z3dTiXRZivdTeeBzDtugNbn3gYTZp U9vOnSctbVdtNXwGhh6Fvy1QHfC/W47MGTX8dcaM= Date: Sat, 18 Apr 2026 00:52:13 -0700 To: mm-commits@vger.kernel.org,skhawaja@google.com,shuah@kernel.org,rppt@kernel.org,pratyush@kernel.org,dmatlack@google.com,brauner@kernel.org,pasha.tatashin@soleen.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] liveupdate-prevent-double-management-of-files.patch removed from -mm tree Message-Id: <20260418075217.4BBA2C19424@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: liveupdate: prevent double management of files has been removed from the -mm tree. Its filename was liveupdate-prevent-double-management-of-files.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Pasha Tatashin Subject: liveupdate: prevent double management of files Date: Thu, 26 Mar 2026 16:39:41 +0000 Patch series "liveupdate: prevent double preservation", v4. Currently, LUO does not prevent the same file from being managed twice across different active sessions. Because LUO preserves files of absolutely different types: memfd, and upcoming vfiofd [1], iommufd [2], guestmefd (and possible kvmfd/cpufd). There is no common private data or guarantee on how to prevent that the same file is not preserved twice beside using inode or some slower and expensive method like hashtables. This patch (of 4) Currently, LUO does not prevent the same file from being managed twice across different active sessions. Use a global xarray luo_preserved_files to keep track of file identifiers being preserved by LUO. Update luo_preserve_file() to check and insert the file identifier into this xarray when it is preserved, and erase it in luo_file_unpreserve_files() when it is released. To allow handlers to define what constitutes a "unique" file (e.g., different struct file objects pointing to the same hardware resource), add a get_id() callback to struct liveupdate_file_ops. If not provided, the default identifier is the struct file pointer itself. This ensures that the same file (or resource) cannot be managed by multiple sessions. If another session attempts to preserve an already managed file, it will now fail with -EBUSY. Link: https://lore.kernel.org/20260326163943.574070-1-pasha.tatashin@soleen.com Link: https://lore.kernel.org/20260326163943.574070-2-pasha.tatashin@soleen.com Link: https://lore.kernel.org/all/20260129212510.967611-1-dmatlack@google.com [1] Link: https://lore.kernel.org/all/20260203220948.2176157-1-skhawaja@google.com [2] Signed-off-by: Pasha Tatashin Reviewed-by: Samiullah Khawaja Reviewed-by: Mike Rapoport (Microsoft) Cc: David Matlack Cc: Pratyush Yadav Cc: Shuah Khan Cc: Christian Brauner Signed-off-by: Andrew Morton --- include/linux/liveupdate.h | 2 ++ kernel/liveupdate/luo_file.c | 32 ++++++++++++++++++++++++++++++-- 2 files changed, 32 insertions(+), 2 deletions(-) --- a/include/linux/liveupdate.h~liveupdate-prevent-double-management-of-files +++ a/include/linux/liveupdate.h @@ -63,6 +63,7 @@ struct liveupdate_file_op_args { * finish, in order to do successful finish calls for all * resources in the session. * @finish: Required. Final cleanup in the new kernel. + * @get_id: Optional. Returns a unique identifier for the file. * @owner: Module reference * * All operations (except can_preserve) receive a pointer to a @@ -78,6 +79,7 @@ struct liveupdate_file_ops { int (*retrieve)(struct liveupdate_file_op_args *args); bool (*can_finish)(struct liveupdate_file_op_args *args); void (*finish)(struct liveupdate_file_op_args *args); + unsigned long (*get_id)(struct file *file); struct module *owner; }; --- a/kernel/liveupdate/luo_file.c~liveupdate-prevent-double-management-of-files +++ a/kernel/liveupdate/luo_file.c @@ -108,12 +108,16 @@ #include #include #include +#include #include #include #include "luo_internal.h" 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 \ @@ -203,6 +207,12 @@ static void luo_free_files_mem(struct lu file_set->files = NULL; } +static unsigned long luo_get_id(struct liveupdate_file_handler *fh, + struct file *file) +{ + return fh->ops->get_id ? fh->ops->get_id(file) : (unsigned long)file; +} + static bool luo_token_is_used(struct luo_file_set *file_set, u64 token) { struct luo_file *iter; @@ -248,6 +258,7 @@ static bool luo_token_is_used(struct luo * Context: Can be called from an ioctl handler during normal system operation. * Return: 0 on success. Returns a negative errno on failure: * -EEXIST if the token is already used. + * -EBUSY if the file descriptor is already preserved by another session. * -EBADF if the file descriptor is invalid. * -ENOSPC if the file_set is full. * -ENOENT if no compatible handler is found. @@ -288,10 +299,15 @@ int luo_preserve_file(struct luo_file_se if (err) goto err_free_files_mem; - err = luo_flb_file_preserve(fh); + err = xa_insert(&luo_preserved_files, luo_get_id(fh, file), + file, GFP_KERNEL); if (err) goto err_free_files_mem; + err = luo_flb_file_preserve(fh); + if (err) + goto err_erase_xa; + luo_file = kzalloc_obj(*luo_file); if (!luo_file) { err = -ENOMEM; @@ -320,6 +336,8 @@ err_kfree: kfree(luo_file); err_flb_unpreserve: luo_flb_file_unpreserve(fh); +err_erase_xa: + xa_erase(&luo_preserved_files, luo_get_id(fh, file)); err_free_files_mem: luo_free_files_mem(file_set); err_fput: @@ -363,6 +381,8 @@ void luo_file_unpreserve_files(struct lu luo_file->fh->ops->unpreserve(&args); luo_flb_file_unpreserve(luo_file->fh); + xa_erase(&luo_preserved_files, + luo_get_id(luo_file->fh, luo_file->file)); list_del(&luo_file->list); file_set->count--; @@ -606,6 +626,11 @@ int luo_retrieve_file(struct luo_file_se luo_file->file = args.file; /* Get reference so we can keep this file in LUO until finish */ get_file(luo_file->file); + + WARN_ON(xa_insert(&luo_preserved_files, + luo_get_id(luo_file->fh, luo_file->file), + luo_file->file, GFP_KERNEL)); + *filep = luo_file->file; luo_file->retrieve_status = 1; @@ -701,8 +726,11 @@ int luo_file_finish(struct luo_file_set luo_file_finish_one(file_set, luo_file); - if (luo_file->file) + if (luo_file->file) { + xa_erase(&luo_preserved_files, + luo_get_id(luo_file->fh, luo_file->file)); fput(luo_file->file); + } list_del(&luo_file->list); file_set->count--; mutex_destroy(&luo_file->mutex); _ Patches currently in -mm which might be from pasha.tatashin@soleen.com are liveupdate-fix-return-value-on-session-allocation-failure.patch