From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CFF047483; Tue, 20 Aug 2024 00:57:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724115480; cv=none; b=VVSnrVSDHzoijkQ752hpweWaQrfShbT9EujgNEtvohXVmV34nZY+5sfkF+93ve7/hyMX4jVP5kbAkK4Mo8A/gQ1liEHpMkp1XSrIlPhLT1XMCgmHf/NtzJOGM1DA1KQ50GK3HtbPyGZgx6Pz4tCJzv8kxiX8bPXuCf4WOxdvRIk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724115480; c=relaxed/simple; bh=6+SCZX/yFu50CRKwNxt0PxQOMt+yD4Pzzw4jd2yVToo=; h=Date:To:From:Subject:Message-Id; b=nZlWGjePyAN7Y/+OqVt/1DUR9ziLo1HgcUrNbS+xLIJLXx8P5nhhJKCMiuSGu7ju30qBH6FU8WgQTT7NuxYb/2sL0Q86q9brcfxCOnNvaErQuOV6Fg4Ynv1gEPAsqGOszvS+FOdHstqgza3VYYIG4ta23zjNXlDJzkgI2PlDlec= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=K3J900PT; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="K3J900PT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35CAFC32782; Tue, 20 Aug 2024 00:57:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1724115479; bh=6+SCZX/yFu50CRKwNxt0PxQOMt+yD4Pzzw4jd2yVToo=; h=Date:To:From:Subject:From; b=K3J900PTfPVqYcsd2O52EbC7TGGAJ7rbQHdWp7RpCLPY0PCoOOelqWBnu68BJxun8 izY9t0L87rKYM51NBEb1xw1EmHhpyblrQD4b7pN5w5OlZah9tkWk2juETfXF++T21H 2bOehfydyZNE4kN7Orf5WuxmtUqiJJ6Kn5xAGZAQ= Date: Mon, 19 Aug 2024 17:57:58 -0700 To: mm-commits@vger.kernel.org,vbabka@suse.cz,stable@vger.kernel.org,roman.gushchin@linux.dev,rientjes@google.com,penberg@kernel.org,iamjoonsoo.kim@lge.com,cl@linux.com,42.hyeyoo@gmail.com,dakr@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-krealloc-consider-spare-memory-for-__gfp_zero.patch added to mm-unstable branch Message-Id: <20240820005759.35CAFC32782@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: krealloc: consider spare memory for __GFP_ZERO has been added to the -mm mm-unstable branch. Its filename is mm-krealloc-consider-spare-memory-for-__gfp_zero.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-krealloc-consider-spare-memory-for-__gfp_zero.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Danilo Krummrich Subject: mm: krealloc: consider spare memory for __GFP_ZERO Date: Tue, 13 Aug 2024 00:34:34 +0200 As long as krealloc() is called with __GFP_ZERO consistently, starting with the initial memory allocation, __GFP_ZERO should be fully honored. However, if for an existing allocation krealloc() is called with a decreased size, it is not ensured that the spare portion the allocation is zeroed. Thus, if krealloc() is subsequently called with a larger size again, __GFP_ZERO can't be fully honored, since we don't know the previous size, but only the bucket size. Example: buf = kzalloc(64, GFP_KERNEL); memset(buf, 0xff, 64); buf = krealloc(buf, 48, GFP_KERNEL | __GFP_ZERO); /* After this call the last 16 bytes are still 0xff. */ buf = krealloc(buf, 64, GFP_KERNEL | __GFP_ZERO); Fix this, by explicitly setting spare memory to zero, when shrinking an allocation with __GFP_ZERO flag set or init_on_alloc enabled. Link: https://lkml.kernel.org/r/20240812223707.32049-1-dakr@kernel.org Signed-off-by: Danilo Krummrich Acked-by: Vlastimil Babka Acked-by: David Rientjes Cc: Christoph Lameter Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Joonsoo Kim Cc: Pekka Enberg Cc: Roman Gushchin Cc: Signed-off-by: Andrew Morton --- mm/slab_common.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/mm/slab_common.c~mm-krealloc-consider-spare-memory-for-__gfp_zero +++ a/mm/slab_common.c @@ -1273,6 +1273,13 @@ __do_krealloc(const void *p, size_t new_ /* If the object still fits, repoison it precisely. */ if (ks >= new_size) { + /* Zero out spare memory. */ + if (want_init_on_alloc(flags)) { + kasan_disable_current(); + memset((void *)p + new_size, 0, ks - new_size); + kasan_enable_current(); + } + p = kasan_krealloc((void *)p, new_size, flags); return (void *)p; } _ Patches currently in -mm which might be from dakr@kernel.org are mm-vmalloc-implement-vrealloc.patch mm-vmalloc-implement-vrealloc-fix.patch mm-vmalloc-implement-vrealloc-fix-2.patch mm-vmalloc-implement-vrealloc-fix-3.patch mm-vmalloc-implement-vrealloc-fix-4.patch mm-kvmalloc-align-kvrealloc-with-krealloc.patch mm-kvmalloc-align-kvrealloc-with-krealloc-fix.patch mm-kvmalloc-align-kvrealloc-with-krealloc-fix-2.patch mm-kvmalloc-align-kvrealloc-with-krealloc-fix-3.patch mm-krealloc-consider-spare-memory-for-__gfp_zero.patch mm-krealloc-clarify-valid-usage-of-__gfp_zero.patch