From: Dennis Zhou <dennis@kernel.org>
To: Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
Christoph Lameter <cl@linux.com>
Cc: Vlad Buslov <vladbu@mellanox.com>,
kernel-team@fb.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 02/12] percpu: do not search past bitmap when allocating an area
Date: Wed, 27 Feb 2019 21:18:29 -0500 [thread overview]
Message-ID: <20190228021839.55779-3-dennis@kernel.org> (raw)
In-Reply-To: <20190228021839.55779-1-dennis@kernel.org>
pcpu_find_block_fit() guarantees that a fit is found within
PCPU_BITMAP_BLOCK_BITS. Iteration is used to determine the first fit as
it compares against the block's contig_hint. This can lead to
incorrectly scanning past the end of the bitmap. The behavior was okay
given the check after for bit_off >= end and the correctness of the
hints from pcpu_find_block_fit().
This patch fixes this by bounding the end offset by the number of bits
in a chunk.
Signed-off-by: Dennis Zhou <dennis@kernel.org>
---
mm/percpu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index 53bd79a617b1..69ca51d238b5 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -988,7 +988,8 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
/*
* Search to find a fit.
*/
- end = start + alloc_bits + PCPU_BITMAP_BLOCK_BITS;
+ end = min_t(int, start + alloc_bits + PCPU_BITMAP_BLOCK_BITS,
+ pcpu_chunk_map_bits(chunk));
bit_off = bitmap_find_next_zero_area(chunk->alloc_map, end, start,
alloc_bits, align_mask);
if (bit_off >= end)
--
2.17.1
next prev parent reply other threads:[~2019-02-28 2:18 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-28 2:18 [PATCH 00/12] introduce percpu block scan_hint Dennis Zhou
2019-02-28 2:18 ` [PATCH 01/12] percpu: update free path with correct new free region Dennis Zhou
2019-03-02 12:56 ` Peng Fan
2019-02-28 2:18 ` Dennis Zhou [this message]
2019-03-02 13:32 ` [PATCH 02/12] percpu: do not search past bitmap when allocating an area Peng Fan
2019-03-02 22:23 ` Dennis Zhou
2019-03-03 8:41 ` Peng Fan
2019-02-28 2:18 ` [PATCH 03/12] percpu: introduce helper to determine if two regions overlap Dennis Zhou
2019-03-02 13:37 ` Peng Fan
2019-03-02 22:24 ` Dennis Zhou
2019-02-28 2:18 ` [PATCH 04/12] percpu: manage chunks based on contig_bits instead of free_bytes Dennis Zhou
2019-03-02 13:48 ` Peng Fan
2019-03-02 22:32 ` Dennis Zhou
2019-03-03 8:42 ` Peng Fan
2019-02-28 2:18 ` [PATCH 05/12] percpu: relegate chunks unusable when failing small allocations Dennis Zhou
2019-03-02 13:55 ` Peng Fan
2019-03-02 22:34 ` Dennis Zhou
2019-02-28 2:18 ` [PATCH 06/12] percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Dennis Zhou
2019-03-03 4:56 ` Peng Fan
2019-02-28 2:18 ` [PATCH 07/12] percpu: add block level scan_hint Dennis Zhou
2019-03-03 6:01 ` Peng Fan
2019-03-03 20:23 ` Dennis Zhou
2019-03-04 9:36 ` Peng Fan
2019-02-28 2:18 ` [PATCH 08/12] percpu: remember largest area skipped during allocation Dennis Zhou
2019-02-28 2:18 ` [PATCH 09/12] percpu: use block scan_hint to only scan forward Dennis Zhou
2019-02-28 2:18 ` [PATCH 10/12] percpu: make pcpu_block_md generic Dennis Zhou
2019-03-03 6:35 ` Peng Fan
2019-02-28 2:18 ` [PATCH 11/12] percpu: convert chunk hints to be based on pcpu_block_md Dennis Zhou
2019-03-03 8:18 ` Peng Fan
2019-03-03 20:22 ` Dennis Zhou
2019-03-04 6:36 ` Peng Fan
2019-02-28 2:18 ` [PATCH 12/12] percpu: use chunk scan_hint to skip some scanning Dennis Zhou
2019-03-03 8:38 ` Peng Fan
2019-02-28 14:47 ` [PATCH 00/12] introduce percpu block scan_hint Vlad Buslov
2019-03-13 20:19 ` Dennis Zhou
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=20190228021839.55779-3-dennis@kernel.org \
--to=dennis@kernel.org \
--cc=cl@linux.com \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=tj@kernel.org \
--cc=vladbu@mellanox.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).