From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 73F544D98FB for ; Fri, 5 Jun 2026 11:48:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780660103; cv=none; b=aR7Smms24pw0kvyDrXZ4YBuZ48dAnoZEkCSKik81FSroDY1vXK2ePG5B8wO+BpgE7meBEG+sygJOOhNReAblwC0B5kuwYhRhmr1Wubh2riXL8WwUVAyKw9DVFo/yQeY+IjycViO5LB+gK/Lau+JBu/TFrRNDd7nv/S06ivbVvuU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780660103; c=relaxed/simple; bh=Pv0JAn2mh85QGKI7z/Kf3RdsHFh2QxC0MkjsrTyer/4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=g7zCs6B4+Q1ysF7wvhfLtVnL7zaSViqBSR8kAl49Ea5fOKkhMKkrabVOATMyly4qiplUztZDgIs2rMsXW9xp7KA0zfayYBt2sgUlI3hxcsYXt1PunFVvuy6K1jggKFb2sh32H/k7n2L0nTUm1nsL0WH7+TZYUyPZU0Dn4Xgln64= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gQaR97ZI; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gQaR97ZI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCEDC1F00893; Fri, 5 Jun 2026 11:48:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780660101; bh=F+BmeJkpk7lnOtX+3YvPCn5bRjFC6wSEqIYi3NffkYk=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=gQaR97ZIGbsQN1dRhHE4kN85ro6UbhtBym/Qt4GpoIaqTI/ZQ4sZATyoRCsNzjg7o t1QrSxfUQJVa6o1Z0Ig3BaDzDIpVOKs5Dy3XB9ZIeiAQyIRuC5qHLmMzVV7QS3BMuA I72kEh3vLBXZNalw1qAQ212aDm1A8nwjKSk6ujzMgInTG69zFYQlfPHs+SaiVezlyF zZddhFjvCv0f4AO8ppFCBHJhaGbmqRfdm5B2sSXCoPd/j+3Vt8Kyz4XSyEzEmnVgCp cL0TkejaPOP8ItTjJX+BfebVX8hcQh5dYjptIwfKFevNNKCcyV0hWT1ofz8fR1LivF 9ZFaGo1/xIwrg== Message-ID: <2dc81b31-36f5-40fb-ba3d-e3f80d65cc15@kernel.org> Date: Fri, 5 Jun 2026 13:48:16 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm/slub: preserve original size in _kmalloc_nolock_noprof retry path Content-Language: en-US To: hu.shengming@zte.com.cn, harry@kernel.org, akpm@linux-foundation.org Cc: hao.li@linux.dev, cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, zhang.run@zte.com.cn, cai.qu@zte.com.cn References: <202606042027323804pk3MRY42Jy7y42OHAhQZ@zte.com.cn> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/4/26 14:27, hu.shengming@zte.com.cn wrote: > From: Shengming Hu > > _kmalloc_nolock_noprof() retries from the next kmalloc bucket when the > initial allocation fails. The retry currently reuses `size` as the > bucket selector and overwrites it with s->object_size + 1. > > That value is later passed as the original allocation size to > __slab_alloc_node(), slab_post_alloc_hook() and kasan_kmalloc(). On a > successful retry this makes KASAN/slub-debug observe the retry bucket > selector rather than the caller requested size, potentially widening the > valid kmalloc range and hiding overflows. > > Keep the caller requested size separately as orig_size and pass it to > the allocation/debug/KASAN paths. Continue using `size` as the retry cache > selector. > > Fixes: af92793e52c3 ("slab: Introduce kmalloc_nolock() and kfree_nolock()") > Signed-off-by: Shengming Hu Merged to slab/for-next, thanks! > --- > Changes in v2: > - Use an explicit orig_size variable instead of bucket_size, as suggested > by Harry and Vlastimil. > - Link to v1: https://lore.kernel.org/all/20260603211011530GqLSXP_rgcuQdR47IGQLL@zte.com.cn/ > > --- > mm/slub.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 67abbbf68fc1..7e1a1fe5daaa 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -5350,6 +5350,7 @@ EXPORT_SYMBOL(__kmalloc_noprof); > void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, int node) > { > gfp_t alloc_gfp = __GFP_NOWARN | __GFP_NOMEMALLOC | gfp_flags; > + size_t orig_size = size; > struct kmem_cache *s; > bool can_retry = true; > void *ret; > @@ -5398,7 +5399,7 @@ void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, in > * kfence_alloc. Hence call __slab_alloc_node() (at most twice) > * and slab_post_alloc_hook() directly. > */ > - ret = __slab_alloc_node(s, alloc_gfp, node, _RET_IP_, size); > + ret = __slab_alloc_node(s, alloc_gfp, node, _RET_IP_, orig_size); > > /* > * It's possible we failed due to trylock as we preempted someone with > @@ -5422,9 +5423,9 @@ void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, in > success: > maybe_wipe_obj_freeptr(s, ret); > slab_post_alloc_hook(s, NULL, alloc_gfp, 1, &ret, > - slab_want_init_on_alloc(alloc_gfp, s), size); > + slab_want_init_on_alloc(alloc_gfp, s), orig_size); > > - ret = kasan_kmalloc(s, ret, size, alloc_gfp); > + ret = kasan_kmalloc(s, ret, orig_size, alloc_gfp); > return ret; > } > EXPORT_SYMBOL_GPL(_kmalloc_nolock_noprof);