From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta1.migadu.com (out-171.mta1.migadu.com [95.215.58.171]) (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 C9EBA2475CE for ; Tue, 7 Oct 2025 22:52:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759877583; cv=none; b=sj69nb8QG40JC1E5tEXUGPxoKy9RH7aL/T6VCenVOBnmJsZxppFDK7Zgm1mIaYi6hYT1Jm46G+uUAxP5A3KsQb2z6q0OM7DH8YWtK2TH4A4Z2k7+8p4wozEDOUxSdgcO95E1Pq6/Eiua6K3x4Vquck1O8Smw8JWQmfnrY+ESS9Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759877583; c=relaxed/simple; bh=GMp9eOBBxkxCv2LqIY9MRCC0DFxxeBdOrkTDHvDkv00=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=nD/8KH05T5NPo2yGkLMZhd8s7uobR9162TYicw1V+MnXUxAnE8/ZvZF18d9I533ZUYdsiEFeDsRzFPpZ2MEjdHoswda70HOAyniP7pqImqs6V+5lPfhQ8vzjICfN6lqwoMo7gZfvJaiexPuZ5peWk9sqEolphJzGJE7K+/ryTCo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=lXCJDcLG; arc=none smtp.client-ip=95.215.58.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="lXCJDcLG" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1759877576; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+zGrEhn9yIbxrx8akVC6Rjuew94sMfqEV9qMdvVonCg=; b=lXCJDcLGRCwwkU7jnZ6bJv2a3MjwgazcrxC0yJDKX0uEgsGEiDtW8vVSPksXSB0lOUih7r wYcsqQKVxqBhyasR8cNmnFe5KxrJnjYHEonk2ybtQeg1pM1/fxvhkoV16ih1XjUDmeKkRV xPToa6kJLGuv9CFDOcW6yEQpU37guAg= From: Roman Gushchin To: Andrew Morton Cc: linux-kernel@vger.kernel.org, "Matthew Wilcox (Oracle)" , Jan Kara , Dev Jain , linux-mm@kvack.org Subject: Re: [PATCH v3] mm: readahead: make thp readahead conditional to mmap_miss logic In-Reply-To: <20251007153424.1b46a4018e17d5dafd7fb126@linux-foundation.org> (Andrew Morton's message of "Tue, 7 Oct 2025 15:34:24 -0700") References: <20251006175106.377411-1-roman.gushchin@linux.dev> <20251007153424.1b46a4018e17d5dafd7fb126@linux-foundation.org> Date: Tue, 07 Oct 2025 15:52:49 -0700 Message-ID: <87play1fzy.fsf@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Migadu-Flow: FLOW_OUT Andrew Morton writes: > On Mon, 6 Oct 2025 10:51:06 -0700 Roman Gushchin wrote: > >> Commit 4687fdbb805a ("mm/filemap: Support VM_HUGEPAGE for file mappings") >> introduced a special handling for VM_HUGEPAGE mappings: even if the >> readahead is disabled, 1 or 2 HPAGE_PMD_ORDER pages are >> allocated. > > Three years ago. > >> This change causes a significant regression > > So no backport suggested? I guess reasonable given how long 4687fdbb805a has > been in tree. Yes, this was my thinking. Also you need a very specific setup to reveal this regression. >> Signed-off-by: Roman Gushchin >> Cc: Matthew Wilcox (Oracle) >> Cc: Jan Kara >> Cc: Dev Jain > > But I'll slap the Fixes: in there, it might help someone. I'd do exactly what you suggested: Fixes + no stable backport. But I guess it still might end up in the LTS tree thanks to the automation picking up all fixes. Should be ok too. Thanks!