linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Alexander Potapenko <glider@google.com>
To: akpm@linux-foundation.org
Cc: dvyukov@google.com, elver@google.com,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	stable@vger.kernel.org, gregkh@linuxfoundation.org,
	jrdr.linux@gmail.com, Alexander Potapenko <glider@google.com>
Subject: [PATCH v4 2/2] kfence: skip all GFP_ZONEMASK allocations
Date: Wed, 30 Jun 2021 17:02:34 +0200	[thread overview]
Message-ID: <20210630150234.1109496-2-glider@google.com> (raw)
In-Reply-To: <20210630150234.1109496-1-glider@google.com>

Allocation requests outside ZONE_NORMAL (MOVABLE, HIGHMEM or DMA) cannot
be fulfilled by KFENCE, because KFENCE memory pool is located in a
zone different from the requested one.

Because callers of kmem_cache_alloc() may actually rely on the
allocation to reside in the requested zone (e.g. memory allocations done
with __GFP_DMA must be DMAable), skip all allocations done with
GFP_ZONEMASK and/or respective SLAB flags (SLAB_CACHE_DMA and
SLAB_CACHE_DMA32).

Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: stable@vger.kernel.org # 5.12+
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marco Elver <elver@google.com>

---

v2:
 - added parentheses around the GFP clause, as requested by Marco
v3:
 - ignore GFP_ZONEMASK, which also covers __GFP_HIGHMEM and __GFP_MOVABLE
 - move the flag check at the beginning of the function, as requested by
   Souptick Joarder
v4:
 - minor fixes to description and comment formatting
---
 mm/kfence/core.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 33bb20d91bf6a..1cbdb62e6d0fb 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -740,6 +740,15 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags)
 	if (size > PAGE_SIZE)
 		return NULL;
 
+	/*
+	 * Skip allocations from non-default zones, including DMA. We cannot
+	 * guarantee that pages in the KFENCE pool will have the requested
+	 * properties (e.g. reside in DMAable memory).
+	 */
+	if ((flags & GFP_ZONEMASK) ||
+	    (s->flags & (SLAB_CACHE_DMA | SLAB_CACHE_DMA32)))
+		return NULL;
+
 	/*
 	 * allocation_gate only needs to become non-zero, so it doesn't make
 	 * sense to continue writing to it and pay the associated contention
-- 
2.32.0.93.g670b81a890-goog


  reply	other threads:[~2021-06-30 15:02 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-30 15:02 [PATCH v4 1/2] kfence: move the size check to the beginning of __kfence_alloc() Alexander Potapenko
2021-06-30 15:02 ` Alexander Potapenko [this message]
2021-07-05 14:05   ` [PATCH v4 2/2] kfence: skip all GFP_ZONEMASK allocations Marco Elver
2021-07-13 16:19     ` Marco Elver
2021-07-05 18:38   ` Souptick Joarder

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210630150234.1109496-2-glider@google.com \
    --to=glider@google.com \
    --cc=akpm@linux-foundation.org \
    --cc=dvyukov@google.com \
    --cc=elver@google.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=jrdr.linux@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=stable@vger.kernel.org \
    --subject='Re: [PATCH v4 2/2] kfence: skip all GFP_ZONEMASK allocations' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).