linux-kernel - [PATCH AUTOSEL 5.18 06/56] usb: cdns3: fix random warning message when driver load

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Message-Id: <20220814153026.2377377-6-sashal@kernel.org>
Date:   Sun, 14 Aug 2022 11:29:36 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Frank Li <Frank.Li@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <sashal@...nel.org>, peter.chen@...nel.org,
        pawell@...ence.com, linux-usb@...r.kernel.org
Subject: [PATCH AUTOSEL 5.18 06/56] usb: cdns3: fix random warning message when driver load

From: Frank Li <Frank.Li@....com>

[ Upstream commit 8659ab3d936fcf0084676f98b75b317017aa8f82 ]

Warning log:
[    4.141392] Unexpected gfp: 0x4 (GFP_DMA32). Fixing up to gfp: 0xa20 (GFP_ATOMIC). Fix your code!
[    4.150340] CPU: 1 PID: 175 Comm: 1-0050 Not tainted 5.15.5-00039-g2fd9ae1b568c #20
[    4.158010] Hardware name: Freescale i.MX8QXP MEK (DT)
[    4.163155] Call trace:
[    4.165600]  dump_backtrace+0x0/0x1b0
[    4.169286]  show_stack+0x18/0x68
[    4.172611]  dump_stack_lvl+0x68/0x84
[    4.176286]  dump_stack+0x18/0x34
[    4.179613]  kmalloc_fix_flags+0x60/0x88
[    4.183550]  new_slab+0x334/0x370
[    4.186878]  ___slab_alloc.part.108+0x4d4/0x748
[    4.191419]  __slab_alloc.isra.109+0x30/0x78
[    4.195702]  kmem_cache_alloc+0x40c/0x420
[    4.199725]  dma_pool_alloc+0xac/0x1f8
[    4.203486]  cdns3_allocate_trb_pool+0xb4/0xd0

pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
{
	...
	page = kmalloc(sizeof(*page), mem_flags);
	page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
					 &page->dma, mem_flags);
	...
}

kmalloc was called with mem_flags, which is passed down in
cdns3_allocate_trb_pool() and have GFP_DMA32 flags.
kmall_fix_flags() report warning.

GFP_DMA32 is not useful at all. dma_alloc_coherent() will handle
DMA memory region correctly by pool->dev. GFP_DMA32 can be removed
safely.

Signed-off-by: Frank Li <Frank.Li@....com>
Link: https://lore.kernel.org/r/20220609154456.2871672-1-Frank.Li@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/usb/cdns3/cdns3-gadget.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index c4f90b124e55..c7c394402e44 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -220,7 +220,7 @@ int cdns3_allocate_trb_pool(struct cdns3_endpoint *priv_ep)
 
 	if (!priv_ep->trb_pool) {
 		priv_ep->trb_pool = dma_pool_alloc(priv_dev->eps_dma_pool,
-						   GFP_DMA32 | GFP_ATOMIC,
+						   GFP_ATOMIC,
 						   &priv_ep->trb_pool_dma);
 
 		if (!priv_ep->trb_pool)
-- 
2.35.1