linux-kernel - [PATCH] iommu/iova: Free all CPU rcache for retry when iova alloc failure

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Message-ID: <20220304044635.4273-1-yf.wang@mediatek.com>
Date:   Fri, 4 Mar 2022 12:46:34 +0800
From:   <yf.wang@...iatek.com>
To:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        "open list:IOMMU DRIVERS" <iommu@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>
CC:     <wsd_upstream@...iatek.com>, Libo Kang <Libo.Kang@...iatek.com>,
        Ning Li <Ning.Li@...iatek.com>, Yong Wu <Yong.Wu@...iatek.com>,
        Yunfei Wang <yf.wang@...iatek.com>, <stable@...r.kernel.org>
Subject: [PATCH] iommu/iova: Free all CPU rcache for retry when iova alloc failure

From: Yunfei Wang <yf.wang@...iatek.com>

In alloc_iova_fast function, if an iova alloc request fail,
it will free the iova ranges present in the percpu iova
rcaches and free global iova rcache and then retry, but
flushing CPU iova rcaches only for each online CPU, which
will cause incomplete rcache cleaning, and iova rcaches of
not online CPU cannot be flushed, because iova rcaches may
also lead to fragmentation of iova space, so the next retry
action may still be fail.

Based on the above, so need to flushing all iova rcaches
for each possible CPU, use for_each_possible_cpu instead of
for_each_online_cpu like in free_iova_rcaches function,
so that all rcaches can be completely released to try
replenishing IOVAs.

Signed-off-by: Yunfei Wang <yf.wang@...iatek.com>
Cc: <stable@...r.kernel.org> # 5.4.*
---
 drivers/iommu/iova.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index b28c9435b898..5a0637cd7bc2 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -460,7 +460,7 @@ alloc_iova_fast(struct iova_domain *iovad, unsigned long size,

 		/* Try replenishing IOVAs by flushing rcache. */
 		flush_rcache = false;
-		for_each_online_cpu(cpu)
+		for_each_possible_cpu(cpu)
 			free_cpu_cached_iovas(cpu, iovad);
 		free_global_cached_iovas(iovad);
 		goto retry;
-- 
2.18.0