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	Thu, 27 Nov 2025 13:38:05 +0000
Date: Thu, 27 Nov 2025 13:38:05 +0000
From: Matthew Wilcox <willy@infradead.org>
To: Jan Sokolowski <jan.sokolowski@intel.com>
Cc: linux-kernel@vger.kernel.org,
	Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH 1/1] idr: do not create idr if new id would be
 outside given range
Message-ID: <aShUPdV18CIxvV-G@casper.infradead.org>
References: <20251127092732.684959-1-jan.sokolowski@intel.com>
 <20251127092732.684959-2-jan.sokolowski@intel.com>
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In-Reply-To: <20251127092732.684959-2-jan.sokolowski@intel.com>

On Thu, Nov 27, 2025 at 10:27:32AM +0100, Jan Sokolowski wrote:
> @@ -88,6 +89,11 @@ int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)
>  	if (ret)
>  		return ret;
>  
> +	if (WARN_ON_ONCE(id < start || (id >= end && end != 0))) {
> +		idr_remove(idr, id);
> +		return -EINVAL;
> +	}

This is certainly the wrong way to fix any problem that does exist.
And it should return -ENOSPC, not -EINVAL.  -EINVAL is "the arguments
are wrong", not "the data structure is full".

I'll go read the thread now.