netdev - Re: [PATCH net-next v5 2/2] page_pool: Track DMA-mapped pages and unmap them when destroying the pool

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <b75c5329-0049-4c9c-ba79-a1132d848d5d@linux.dev>
Date: Mon, 31 Mar 2025 19:27:40 +0200
From: Zhu Yanjun <yanjun.zhu@...ux.dev>
To: Alexander Lobakin <aleksander.lobakin@...el.com>,
 Toke Høiland-Jørgensen <toke@...hat.com>
Cc: "David S. Miller" <davem@...emloft.net>, Jakub Kicinski
 <kuba@...nel.org>, Jesper Dangaard Brouer <hawk@...nel.org>,
 Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>,
 Tariq Toukan <tariqt@...dia.com>, Andrew Lunn <andrew+netdev@...n.ch>,
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 Ilias Apalodimas <ilias.apalodimas@...aro.org>,
 Simon Horman <horms@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>,
 Mina Almasry <almasrymina@...gle.com>, Yonglong Liu
 <liuyonglong@...wei.com>, Yunsheng Lin <linyunsheng@...wei.com>,
 Pavel Begunkov <asml.silence@...il.com>, Matthew Wilcox
 <willy@...radead.org>, netdev@...r.kernel.org, bpf@...r.kernel.org,
 linux-rdma@...r.kernel.org, linux-mm@...ck.org, Qiuling Ren
 <qren@...hat.com>, Yuying Ma <yuma@...hat.com>
Subject: Re: [PATCH net-next v5 2/2] page_pool: Track DMA-mapped pages and
 unmap them when destroying the pool

在 2025/3/31 18:35, Alexander Lobakin 写道:
> From: Toke Høiland-Jørgensen <toke@...hat.com>
> Date: Fri, 28 Mar 2025 13:19:09 +0100
> 
>> When enabling DMA mapping in page_pool, pages are kept DMA mapped until
>> they are released from the pool, to avoid the overhead of re-mapping the
>> pages every time they are used. This causes resource leaks and/or
>> crashes when there are pages still outstanding while the device is torn
>> down, because page_pool will attempt an unmap through a non-existent DMA
>> device on the subsequent page return.
> 
> [...]
> 
>> @@ -173,10 +212,10 @@ struct page_pool {
>>   	int cpuid;
>>   	u32 pages_state_hold_cnt;
>>   
>> -	bool has_init_callback:1;	/* slow::init_callback is set */
>> +	bool dma_sync;			/* Perform DMA sync for device */
> 
> Have you seen my comment under v3 (sorry but I missed that there was v4
> already)? Can't we just test the bit atomically?

Perhaps test_bit series functions can test the bit atomically. Maybe 
there are more good options about this testing the bit atomically. But 
test_bit should implement the task that tests the bit atomically.

Zhu Yanjun

> 
>>   	bool dma_map:1;			/* Perform DMA mapping */
>> -	bool dma_sync:1;		/* Perform DMA sync for device */
>>   	bool dma_sync_for_cpu:1;	/* Perform DMA sync for cpu */
>> +	bool has_init_callback:1;	/* slow::init_callback is set */
> 
> Thanks,
> Olek