From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Rong Zhang <i@rong.moe>, Jesper Dangaard Brouer <hawk@kernel.org>,
Ilias Apalodimas <ilias.apalodimas@linaro.org>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>,
Mina Almasry <almasrymina@google.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Rong Zhang <i@rong.moe>
Subject: Re: [PATCH] net: page_pool: Remove zone/policy GFP flags when allocating XArray entries
Date: Thu, 20 Aug 2026 22:01:04 +0200 [thread overview]
Message-ID: <87cxvcftof.fsf@toke.dk> (raw)
In-Reply-To: <20260821-page-pool-xa-drop-dma32-v1-1-6eab295c3478@rong.moe>
Rong Zhang <i@rong.moe> writes:
> Net drivers request GFP flags according to both the current context and
> the device constraints, but the XArray entry itself is by no mean used
> by the device. Passing though device constraints to XArray allocation is
> a bug and will be warned and fixed up by slab, e.g.:
>
> Unexpected gfp: 0x4 (GFP_DMA32). Fixing up to gfp: 0x82820 (GFP_ATOMIC|__GFP_NOWARN|__GFP_NOMEMALLOC). Fix your code!
> CPU: 2 UID: 0 PID: 1071629 Comm: kworker/u80:1 Not tainted 7.2.0-rc7+ #1 PREEMPT(lazy)
> Hardware name: LENOVO 21Q4/LNVNB161216, BIOS PXCN27WW 10/20/2025
> Workqueue: mt76 mt792x_pm_wake_work [mt792x_lib]
> Call Trace:
> <TASK>
> dump_stack_lvl+0x6e/0x90
> kmalloc_fix_flags+0x4d/0x6a
> refill_objects+0x10a/0x330
> __pcs_replace_empty_main+0x292/0x5c0
> kmem_cache_alloc_lru_noprof+0x4c2/0x680
> ? __xas_nomem+0x3a/0x120
> __xas_nomem+0x3a/0x120
> __xa_alloc+0xd4/0x190
> page_pool_dma_map+0xef/0x400
> __page_pool_alloc_netmems_slow+0xed/0x480
> ? lock_release+0x280/0x490
> page_pool_alloc_frag_netmem+0xe0/0x3a0
> page_pool_alloc_frag+0xe/0x20
> mt76_dma_rx_fill_buf+0x1f6/0x580 [mt76]
> mt76_dma_rx_reset+0x1cf/0x230 [mt76]
> mt792x_wpdma_reset+0x183/0x1b0 [mt792x_lib]
> mt792x_wpdma_reinit_cond+0x5e/0xa0 [mt792x_lib]
> mt792xe_mcu_drv_pmctrl+0x28/0x60 [mt792x_lib]
> mt792x_mcu_drv_pmctrl+0x3e/0x90 [mt792x_lib]
> mt792x_pm_wake_work+0x2d/0x1d0 [mt792x_lib]
> ? process_one_work+0x20e/0x600
> process_one_work+0x230/0x600
> ? process_one_work+0x256/0x600
> worker_thread+0x1ec/0x3c0
> ? rescuer_thread+0x610/0x610
> kthread+0xf2/0x130
> ? kthread_affine_node+0x140/0x140
> ret_from_fork+0x2a5/0x380
> ? kthread_affine_node+0x140/0x140
> ret_from_fork_asm+0x11/0x20
> </TASK>
>
> Currently mt76 and stmmac may allocate page pool pages with GFP_DMA32.
>
> Fix it by removing zone/policy GFP flags when allocating XArray entries.
> This is inspired by commit 96d578088085 ("iommu/dma: Use the gfp
> parameter in __iommu_dma_alloc_noncontiguous()").
>
> Fixes: ee62ce7a1d90 ("page_pool: Track DMA-mapped pages and unmap them when destroying the pool")
> Signed-off-by: Rong Zhang <i@rong.moe>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
prev parent reply other threads:[~2026-08-20 20:01 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-20 17:41 Rong Zhang
2026-08-20 20:01 ` Toke Høiland-Jørgensen [this message]
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