linux-kernel - Re: [PATCH v2 00/24] ext4: enable block size larger than page size

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Message-ID: <20251112040220.GO2988753@mit.edu>
Date: Tue, 11 Nov 2025 23:02:20 -0500
From: "Theodore Ts'o" <tytso@....edu>
To: Baokun Li <libaokun1@...wei.com>
Cc: linux-ext4@...r.kernel.org, adilger.kernel@...ger.ca, jack@...e.cz,
        linux-kernel@...r.kernel.org, kernel@...kajraghav.com,
        mcgrof@...nel.org, ebiggers@...nel.org, willy@...radead.org,
        yi.zhang@...wei.com, yangerkun@...wei.com, chengzhihao1@...wei.com,
        Baokun Li <libaokun@...weicloud.com>
Subject: Re: [PATCH v2 00/24] ext4: enable block size larger than page size

On Wed, Nov 12, 2025 at 10:19:06AM +0800, Baokun Li wrote:
> I am using a slightly older version of xfstests, and when running the
> 64k tests I also encountered similar failures. The cover letter stated
> "no Oops" for the 64k tests rather than "no new failures," meaning that
> some cases did fail, but no severe issues such as BUG_ON or softlock
> were observed.

Sorry, I misread your cover letter.  It's good you are seeing similar
failures.


On Wed, Nov 12, 2025 at 10:49:19AM +0800, Baokun Li wrote:
> I checked the code of the swapon syscall in mm/swapfile.c, and currently
> the swapfile does not support LBS. Therefore, some failing test cases can
> be filtered out based on this.

Ah, OK. What's happening is with XFS the swap tests are being skipped
automatically if the swapon fails.  From _require_scratch_swapfils:

	*)
		if ! swapon "$SCRATCH_MNT/swap" >/dev/null 2>&1; then
			_scratch_unmount
			_notrun "swapfiles are not supported"
		fi
		;;


But ext4 has different logic:

	# ext* has supported all variants of swap files since their
	# introduction, so swapon should not fail.

<< famous last words >>

	case "$FSTYP" in
	ext2|ext3|ext4)
		if ! swapon "$SCRATCH_MNT/swap" >/dev/null 2>&1; then
			if _check_s_dax "$SCRATCH_MNT/swap" 1 >/dev/null; then
				_scratch_unmount
				_notrun "swapfiles are not supported"
			else
				_scratch_unmount
				_fail "swapon failed for $FSTYP"
			fi
		fi
		;;


I guess we could add logic to _require_scratch_swapfile in common/rc
to also _notrun if swapon fails and block size is greater that page
size.  Or I might just add an exclusion in my test appliance runner
for now for all tests in group swap.

						- Ted