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From:   David Howells <dhowells@redhat.com>
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To:     Krzysztof Kozlowski <krzk@kernel.org>
Cc:     dhowells@redhat.com,
        Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        linux-nfs@vger.kernel.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Scott Mayhew <smayhew@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>
Subject: Re: [BISECT BUG] NFS v4 root not working after 6d972518b821 ("NFS: Add fs_context support.")
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Date:   Fri, 17 Jan 2020 14:20:03 +0000
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You seem to be running afoul of the check here:

	case Opt_minorversion:
		if (result.uint_32 > NFS4_MAX_MINOR_VERSION)
			goto out_of_bounds;
		ctx->minorversion = result.uint_32;
		break;

which would seem to indicate that the mount process is supplying
minorversion=X as an option.  Can you modify your kernel to print param->key
and param->string at the top of nfs_fs_context_parse_param()?  Adding
something like:

	pr_notice("NFSOP '%s=%s'\n", param->key, param->string);

will likely suffice unless you're directly driving the new mount API - in
which case param->string might be things other than a string, but that's
unlikely.  It might also be NULL, but printk should handle that.

David