From: Matteo Croce <mcroce@linux.microsoft.com>
To: netdev@vger.kernel.org, linux-mm@kvack.org
Cc: Ayush Sawal <ayush.sawal@chelsio.com>,
Vinay Kumar Yadav <vinay.yadav@chelsio.com>,
Rohit Maheshwari <rohitm@chelsio.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
Marcin Wojtas <mw@semihalf.com>,
Russell King <linux@armlinux.org.uk>,
Mirko Lindner <mlindner@marvell.com>,
Stephen Hemminger <stephen@networkplumber.org>,
Tariq Toukan <tariqt@nvidia.com>,
Jesper Dangaard Brouer <hawk@kernel.org>,
Ilias Apalodimas <ilias.apalodimas@linaro.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Boris Pismenny <borisp@nvidia.com>, Arnd Bergmann <arnd@arndb.de>,
Andrew Morton <akpm@linux-foundation.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>, Yu Zhao <yuzhao@google.com>,
Will Deacon <will@kernel.org>, Fenghua Yu <fenghua.yu@intel.com>,
Roman Gushchin <guro@fb.com>, Hugh Dickins <hughd@google.com>,
Peter Xu <peterx@redhat.com>, Jason Gunthorpe <jgg@ziepe.ca>,
Jonathan Lemon <jonathan.lemon@gmail.com>,
Alexander Lobakin <alobakin@pm.me>,
Cong Wang <cong.wang@bytedance.com>, wenxu <wenxu@ucloud.cn>,
Kevin Hao <haokexin@gmail.com>,
Jakub Sitnicki <jakub@cloudflare.com>,
Marco Elver <elver@google.com>,
Willem de Bruijn <willemb@google.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Yunsheng Lin <linyunsheng@huawei.com>,
Guillaume Nault <gnault@redhat.com>,
linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org,
bpf@vger.kernel.org, Matthew Wilcox <willy@infradead.org>,
Eric Dumazet <edumazet@google.com>,
David Ahern <dsahern@gmail.com>,
Lorenzo Bianconi <lorenzo@kernel.org>,
Saeed Mahameed <saeedm@nvidia.com>, Andrew Lunn <andrew@lunn.ch>,
Paolo Abeni <pabeni@redhat.com>,
Sven Auhagen <sven.auhagen@voleatech.de>
Subject: [PATCH net-next v5 1/5] mm: add a signature in struct page
Date: Thu, 13 May 2021 18:58:42 +0200 [thread overview]
Message-ID: <20210513165846.23722-2-mcroce@linux.microsoft.com> (raw)
In-Reply-To: <20210513165846.23722-1-mcroce@linux.microsoft.com>
From: Matteo Croce <mcroce@microsoft.com>
This is needed by the page_pool to avoid recycling a page not allocated
via page_pool.
The page->signature field is aliased to page->lru.next and
page->compound_head, but it can't be set by mistake because the
signature value is a bad pointer, and can't trigger a false positive
in PageTail() because the last bit is 0.
Co-developed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
---
include/linux/mm.h | 12 +++++++-----
include/linux/mm_types.h | 12 ++++++++++++
include/net/page_pool.h | 2 ++
net/core/page_pool.c | 4 ++++
4 files changed, 25 insertions(+), 5 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 322ec61d0da7..48268d2d0282 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1668,10 +1668,12 @@ struct address_space *page_mapping(struct page *page);
static inline bool page_is_pfmemalloc(const struct page *page)
{
/*
- * Page index cannot be this large so this must be
- * a pfmemalloc page.
+ * This is not a tail page; compound_head of a head page is unused
+ * at return from the page allocator, and will be overwritten
+ * by callers who do not care whether the page came from the
+ * reserves.
*/
- return page->index == -1UL;
+ return page->compound_head & 2;
}
/*
@@ -1680,12 +1682,12 @@ static inline bool page_is_pfmemalloc(const struct page *page)
*/
static inline void set_page_pfmemalloc(struct page *page)
{
- page->index = -1UL;
+ page->compound_head = 2;
}
static inline void clear_page_pfmemalloc(struct page *page)
{
- page->index = 0;
+ page->compound_head = 0;
}
/*
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 5aacc1c10a45..44cf328e94e2 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -96,6 +96,18 @@ struct page {
unsigned long private;
};
struct { /* page_pool used by netstack */
+ /**
+ * @pp_magic: magic value to avoid recycling non
+ * page_pool allocated pages.
+ * It aliases with page->lru.next
+ */
+ unsigned long pp_magic;
+ /**
+ * @pp: pointer to page_pool.
+ * It aliases with page->lru.prev
+ */
+ struct page_pool *pp;
+ unsigned long _pp_mapping_pad;
/**
* @dma_addr: might require a 64-bit value on
* 32-bit architectures.
diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index b4b6de909c93..24b3d42c62c0 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -63,6 +63,8 @@
*/
#define PP_ALLOC_CACHE_SIZE 128
#define PP_ALLOC_CACHE_REFILL 64
+#define PP_SIGNATURE (POISON_POINTER_DELTA + 0x40)
+
struct pp_alloc_cache {
u32 count;
struct page *cache[PP_ALLOC_CACHE_SIZE];
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 3c4c4c7a0402..9de5d8c08c17 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -221,6 +221,8 @@ static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
return NULL;
}
+ page->pp_magic = PP_SIGNATURE;
+
/* Track how many pages are held 'in-flight' */
pool->pages_state_hold_cnt++;
trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
@@ -341,6 +343,8 @@ void page_pool_release_page(struct page_pool *pool, struct page *page)
DMA_ATTR_SKIP_CPU_SYNC);
page_pool_set_dma_addr(page, 0);
skip_dma_unmap:
+ page->pp_magic = 0;
+
/* This may be the last page returned, releasing the pool, so
* it is not safe to reference pool afterwards.
*/
--
2.31.1
next prev parent reply other threads:[~2021-05-13 16:59 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-13 16:58 [PATCH net-next v5 0/5] page_pool: recycle buffers Matteo Croce
2021-05-13 16:58 ` Matteo Croce [this message]
2021-05-14 1:00 ` [PATCH net-next v5 1/5] mm: add a signature in struct page Matthew Wilcox
2021-05-14 1:34 ` Matteo Croce
2021-05-18 15:44 ` Matteo Croce
2021-05-13 16:58 ` [PATCH net-next v5 2/5] skbuff: add a parameter to __skb_frag_unref Matteo Croce
2021-05-13 16:58 ` [PATCH net-next v5 3/5] page_pool: Allow drivers to hint on SKB recycling Matteo Croce
2021-05-14 3:39 ` Yunsheng Lin
2021-05-14 7:36 ` Ilias Apalodimas
2021-05-14 8:31 ` Yunsheng Lin
2021-05-14 9:17 ` Ilias Apalodimas
2021-05-15 2:07 ` Yunsheng Lin
2021-05-17 6:38 ` Ilias Apalodimas
2021-05-17 8:25 ` Yunsheng Lin
2021-05-17 9:36 ` Ilias Apalodimas
2021-05-17 11:10 ` Yunsheng Lin
2021-05-17 11:35 ` Ilias Apalodimas
2021-05-13 16:58 ` [PATCH net-next v5 4/5] mvpp2: recycle buffers Matteo Croce
2021-05-13 18:20 ` Russell King (Oracle)
2021-05-13 23:52 ` Matteo Croce
2021-05-13 16:58 ` [PATCH net-next v5 5/5] mvneta: " Matteo Croce
2021-05-13 18:25 ` Russell King (Oracle)
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