linux-kernel - Coverity: zblock_reclaim_block(): Control flow issues

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Message-ID: <202211171421.914F0F3719@keescook>
Date:   Thu, 17 Nov 2022 14:21:46 -0800
From:   coverity-bot <keescook@...omium.org>
To:     Ananda <a.badmaev@...cknet.pro>
Cc:     Jonathan Corbet <corbet@....net>, linux-kernel@...r.kernel.org,
        Minchan Kim <minchan@...nel.org>,
        Ananda Badmaev <a.badmaev@...cknet.pro>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        linux-mm@...ck.org, linux-doc@...r.kernel.org,
        Vitaly Wool <vitaly.wool@...sulko.com>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        linux-next@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Coverity: zblock_reclaim_block(): Control flow issues

Hello!

This is an experimental semi-automated report about issues detected by
Coverity from a scan of next-20221117 as part of the linux-next scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan

You're getting this email because you were associated with the identified
lines of code (noted below) that were touched by commits:

  Wed Nov 16 16:19:12 2022 -0800
    9097e28c25c8 ("mm: add zblock - new allocator for use via zpool API")

Coverity reported the following:

*** CID 1527349:  Control flow issues  (NO_EFFECT)
mm/zblock.c:412 in zblock_reclaim_block()
406     	unsigned long handle, block_type, slot;
407     	int ret, i, reclaimed;
408
409     	/* start with list storing blocks with the worst compression and try
410     	 * to evict the first added (oldest) block in this list
411     	 */
vvv     CID 1527349:  Control flow issues  (NO_EFFECT)
vvv     This greater-than-or-equal-to-zero comparison of an unsigned value is always true. "block_type >= 0UL".
412     	for (block_type = ARRAY_SIZE(block_desc) - 1; block_type >= 0; --block_type) {
413     		list = &(pool->block_lists[block_type]);
414     		spin_lock(&list->lock);
415
416     		/* find the oldest block in list */
417     		block = list_last_entry(&list->head, struct zblock_block, block_node);

If this is a false positive, please let us know so we can mark it as
such, or teach the Coverity rules to be smarter. If not, please make
sure fixes get into linux-next. :) For patches fixing this, please
include these lines (but double-check the "Fixes" first):

Reported-by: coverity-bot <keescook+coverity-bot@...omium.org>
Addresses-Coverity-ID: 1527349 ("Control flow issues")
Fixes: 9097e28c25c8 ("mm: add zblock - new allocator for use via zpool API")

Thanks for your attention!

-- 
Coverity-bot