From: Sidhartha Kumar <sidhartha.kumar@oracle.com>
To: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
maple-tree@lists.infradead.org
Cc: akpm@linux-foundation.org, willy@infradead.org,
liam.howlett@oracle.com, zhangpeng.00@bytedance.com,
stable@vger.kernel.org
Subject: Re: [PATCH V2] maple_tree: do not preallocate nodes for slot stores
Date: Wed, 13 Dec 2023 13:03:29 -0800 [thread overview]
Message-ID: <31d24c29-5b7c-328c-b830-276acab43203@oracle.com> (raw)
In-Reply-To: <20231213205058.386589-1-sidhartha.kumar@oracle.com>
On 12/13/23 12:50 PM, Sidhartha Kumar wrote:
> mas_preallocate() defaults to requesting 1 node for preallocation and then
> ,depending on the type of store, will update the request variable. There
> isn't a check for a slot store type, so slot stores are preallocating the
> default 1 node. Slot stores do not require any additional nodes, so add a
> check for the slot store case that will bypass node_count_gfp(). Update
> the tests to reflect that slot stores do not require allocations.
>
> User visible effects of this bug include increased memory usage from the
> unneeded node that was allocated.
>
> Fixes: 0b8bb544b1a7 ("maple_tree: update mas_preallocate() testing")
> Cc: <stable@vger.kernel.org> # 6.6+
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> ---
> v1->v2:
> fix coding style per Matthew and Andrew
> use wr_mas->node_end to fix build error
>
When this is merged to mm-unstable could the following fixlet be applied to be
compatible with Liam's series[1]:
[1]:
https://lore.kernel.org/all/20231101171629.3612299-5-Liam.Howlett@oracle.com/T/#mc0e5000f6de822182bf7579c230030c5ec4ec1a7
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 1130803b9d3f7..c9a970ea20dd5 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5477,7 +5477,7 @@ int mas_preallocate(struct ma_state *mas, void *entry,
gfp_t gfp)
node_size = mas_wr_new_end(&wr_mas);
/* Slot store, does not require additional nodes */
- if (node_size == wr_mas.node_end) {
+ if (node_size == mas->end) {
/* reuse node */
if (!mt_in_rcu(mas->tree))
return 0;
>
> lib/maple_tree.c | 11 +++++++++++
> tools/testing/radix-tree/maple.c | 2 +-
> 2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index bb24d84a4922f..684689457d77f 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -5501,6 +5501,17 @@ int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp)
>
> mas_wr_end_piv(&wr_mas);
> node_size = mas_wr_new_end(&wr_mas);
> +
> + /* Slot store, does not require additional nodes */
> + if (node_size == wr_mas.node_end) {
> + /* reuse node */
> + if (!mt_in_rcu(mas->tree))
> + return 0;
> + /* shifting boundary */
> + if (wr_mas.offset_end - mas->offset == 1)
> + return 0;
> + }
> +
> if (node_size >= mt_slots[wr_mas.type]) {
> /* Split, worst case for now. */
> request = 1 + mas_mt_height(mas) * 2;
> diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
> index e5da1cad70baf..76a8990bb14e8 100644
> --- a/tools/testing/radix-tree/maple.c
> +++ b/tools/testing/radix-tree/maple.c
> @@ -35538,7 +35538,7 @@ static noinline void __init check_prealloc(struct maple_tree *mt)
> MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> allocated = mas_allocated(&mas);
> height = mas_mt_height(&mas);
> - MT_BUG_ON(mt, allocated != 1);
> + MT_BUG_ON(mt, allocated != 0);
> mas_store_prealloc(&mas, ptr);
> MT_BUG_ON(mt, mas_allocated(&mas) != 0);
>
next prev parent reply other threads:[~2023-12-13 21:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-13 20:50 [PATCH V2] maple_tree: do not preallocate nodes for slot stores Sidhartha Kumar
2023-12-13 21:03 ` Sidhartha Kumar [this message]
2023-12-13 21:09 ` Andrew Morton
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=31d24c29-5b7c-328c-b830-276acab43203@oracle.com \
--to=sidhartha.kumar@oracle.com \
--cc=akpm@linux-foundation.org \
--cc=liam.howlett@oracle.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=maple-tree@lists.infradead.org \
--cc=stable@vger.kernel.org \
--cc=willy@infradead.org \
--cc=zhangpeng.00@bytedance.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).