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 8442D3B83F9 for ; Tue, 29 Sep 2026 21:13:25 +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=1790716407; cv=none; b=c954jilQE6jcAJ19Hh0T2JVLMHb6PHwsHAwXhnqSRub0gCzHYcy79A4a/bVN1o32uCTMqV/qeU0JxqEA/ZcxFZHNwCkcLEOszaJgmzPMNXTpFm4vX7pRGL5KgLHhBDuOtP5NLKvZqAYJCPrjbxJjkSRhYNHWNLO1B1D70sdoRxw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790716407; c=relaxed/simple; bh=sxE6EwYzus1GssTUTr/E/NrFQUzeS5swqpU+L1xa3PA=; h=Date:To:From:Subject:Message-Id; b=qKRdV6ibeFjz2RJsu6m4nshBZLX8on9jaAqBrDyc7yI3Kp0WR0aJfoYZzPWmBa4SdYMKjJ1hTblFGlBnfQ0W5/wC1hWvYqj4MbRs/aVZKbcqQohIT5H8DAnSjUDSMazwpj+PUjPIN7FZ6A+6NfTtk10aOOR9jXILNfvwg/eSsys= 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=nynqS5k+; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="nynqS5k+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE8461F000FF; Tue, 29 Sep 2026 21:13:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1790716405; bh=XeR3cIKEhwZ0mU6II0gc/g8MeFa9Ksw6H6n+iU+hfgw=; h=Date:To:From:Subject; b=nynqS5k+6as2Oa9B/rnAddhqZe2KDP2cmFamPu3jDJwp+BDFnRPorEEmOIiVqMFhq PjNVdIg+ZPqI9l2ccB5bN9F2X68Z5/KsCzSz6SPkoJQ+cVLco+hANDttJbt9QgrWej sAHlie/icgy0U9xZ8CoODl8N6orY265GXD3UfMZo= Date: Tue, 29 Sep 2026 14:13:24 -0700 To: mm-commits@vger.kernel.org,senozhatsky@chromium.org,minchan@kernel.org,axboe@kernel.dk,pooyan.azadparvar@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: + zram-fix-short-reads-from-block_state.patch added to mm-new branch Message-Id: <20260929211324.EE8461F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: zram: fix short reads from block_state has been added to the -mm mm-new branch. Its filename is zram-fix-short-reads-from-block_state.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-fix-short-reads-from-block_state.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Pooyan Azad Subject: zram: fix short reads from block_state Date: Tue, 29 Sep 2026 09:18:46 +0200 read_block_state() formats each entry directly into the buffer supplied by read(). If the remaining buffer is too small for one complete record, snprintf() returns the full record length and the function stops without copying data or advancing the file position. A read from this debugfs file which is smaller than a record therefore returns zero at a non-EOF position and cannot make progress. Convert block_state to seq_file so formatted records are buffered independently of the userspace read size. Keep dev_lock held across each seq_file iteration and continue to protect individual entries with their slot locks. Link: https://lore.kernel.org/20260929071846.24829-1-pooyan.azadparvar@gmail.com Fixes: c0265342bff4 ("zram: introduce zram memory tracking") Signed-off-by: Pooyan Azad Signed-off-by: Andrew Morton Closes: https://lore.kernel.org/r/CANC3H+LdtoydSp+o2ecErAw7k6R2+gRf9LyxcaoHv_mGhJmyQQ@mail.gmail.com/ Reviewed-by: Sergey Senozhatsky Tested-by: Sergey Senozhatsky Cc: Minchan Kim Cc: Jens Axboe --- drivers/block/zram/zram_drv.c | 104 ++++++++++++++++---------------- 1 file changed, 53 insertions(+), 51 deletions(-) --- a/drivers/block/zram/zram_drv.c~zram-fix-short-reads-from-block_state +++ a/drivers/block/zram/zram_drv.c @@ -1553,68 +1553,70 @@ static void zram_debugfs_destroy(void) debugfs_remove_recursive(zram_debugfs_root); } -static ssize_t read_block_state(struct file *file, char __user *buf, - size_t count, loff_t *ppos) +static void *zram_block_state_start(struct seq_file *seq, loff_t *pos) { - char *kbuf; - unsigned long index; - ssize_t written = 0; - struct zram *zram = file->private_data; + struct zram *zram = seq->private; unsigned long nr_pages; - kbuf = kvmalloc(count, GFP_KERNEL); - if (!kbuf) - return -ENOMEM; - - guard(rwsem_read)(&zram->dev_lock); - if (!init_done(zram)) { - kvfree(kbuf); - return -EINVAL; - } + down_read(&zram->dev_lock); + if (!init_done(zram)) + return ERR_PTR(-EINVAL); nr_pages = zram->disksize >> PAGE_SHIFT; + if (*pos >= nr_pages) + return NULL; - for (index = *ppos; index < nr_pages; index++) { - int copied; + return pos; +} - slot_lock(zram, index); - if (!slot_allocated(zram, index)) - goto next; - - copied = snprintf(kbuf + written, count, - "%12lu %12u.%06d %c%c%c%c%c%c\n", - index, zram->table[index].attr.ac_time, 0, - test_slot_flag(zram, index, ZRAM_SAME) ? 's' : '.', - test_slot_flag(zram, index, ZRAM_WB) ? 'w' : '.', - test_slot_flag(zram, index, ZRAM_HUGE) ? 'h' : '.', - test_slot_flag(zram, index, ZRAM_IDLE) ? 'i' : '.', - get_slot_comp_priority(zram, index) ? 'r' : '.', - test_slot_flag(zram, index, - ZRAM_INCOMPRESSIBLE) ? 'n' : '.'); - - if (count <= copied) { - slot_unlock(zram, index); - break; - } - written += copied; - count -= copied; -next: - slot_unlock(zram, index); - *ppos += 1; - } +static void *zram_block_state_next(struct seq_file *seq, void *v, loff_t *pos) +{ + struct zram *zram = seq->private; + unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; + + ++*pos; + if (*pos >= nr_pages) + return NULL; + + return pos; +} - if (copy_to_user(buf, kbuf, written)) - written = -EFAULT; - kvfree(kbuf); +static void zram_block_state_stop(struct seq_file *seq, void *v) +{ + struct zram *zram = seq->private; + + up_read(&zram->dev_lock); +} + +static int zram_block_state_show(struct seq_file *seq, void *v) +{ + struct zram *zram = seq->private; + unsigned long index = *(loff_t *)v; + + slot_lock(zram, index); + if (slot_allocated(zram, index)) { + seq_printf(seq, "%12lu %12u.%06d %c%c%c%c%c%c\n", + index, zram->table[index].attr.ac_time, 0, + test_slot_flag(zram, index, ZRAM_SAME) ? 's' : '.', + test_slot_flag(zram, index, ZRAM_WB) ? 'w' : '.', + test_slot_flag(zram, index, ZRAM_HUGE) ? 'h' : '.', + test_slot_flag(zram, index, ZRAM_IDLE) ? 'i' : '.', + get_slot_comp_priority(zram, index) ? 'r' : '.', + test_slot_flag(zram, index, + ZRAM_INCOMPRESSIBLE) ? 'n' : '.'); + } + slot_unlock(zram, index); - return written; + return 0; } -static const struct file_operations proc_zram_block_state_op = { - .open = simple_open, - .read = read_block_state, - .llseek = default_llseek, +static const struct seq_operations zram_block_state_sops = { + .start = zram_block_state_start, + .next = zram_block_state_next, + .stop = zram_block_state_stop, + .show = zram_block_state_show, }; +DEFINE_SEQ_ATTRIBUTE(zram_block_state); static void zram_debugfs_register(struct zram *zram) { @@ -1624,7 +1626,7 @@ static void zram_debugfs_register(struct zram->debugfs_dir = debugfs_create_dir(zram->disk->disk_name, zram_debugfs_root); debugfs_create_file("block_state", 0400, zram->debugfs_dir, - zram, &proc_zram_block_state_op); + zram, &zram_block_state_fops); } static void zram_debugfs_unregister(struct zram *zram) _ Patches currently in -mm which might be from pooyan.azadparvar@gmail.com are zram-fix-short-reads-from-block_state.patch