Andrew Morton wrote:
On Mon, 11 Dec 2006 11:07:06 -0500
Jeff Garzik <jeff@xxxxxxxxxx> wrote:
Andrew Morton wrote:
[ 231.948000] SCSI device sda: 195371568 512-byte hdwr sectors (100030 MB)
[ 232.232000] ata1.00: configured for UDMA/33
[ 232.404000] WARNING (1) at arch/i386/mm/highmem.c:47 kmap_atomic()
It's using KM_USER0 from softirq.
I thought that was OK if it was kmap_atomic(). Live and learn.
Each kmap_atomic slot is basically a per-cpu global variable. If a CPU is
inside process-level kmap_atomic(KM_USER0) and then runs that softirq,
it'll return from the softirq with its kmap slot pointing at the wrong
page.
Checked in the attached.
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 664e137..a4790be 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1539,7 +1539,7 @@ static unsigned int ata_scsi_rbuf_get(st
struct scatterlist *sg;
sg = (struct scatterlist *) cmd->request_buffer;
- buf = kmap_atomic(sg->page, KM_USER0) + sg->offset;
+ buf = kmap_atomic(sg->page, KM_IRQ0) + sg->offset;
buflen = sg->length;
} else {
buf = cmd->request_buffer;
@@ -1567,7 +1567,7 @@ static inline void ata_scsi_rbuf_put(str
struct scatterlist *sg;
sg = (struct scatterlist *) cmd->request_buffer;
- kunmap_atomic(buf - sg->offset, KM_USER0);
+ kunmap_atomic(buf - sg->offset, KM_IRQ0);
}
}
KM_IRQ0 can only be used with local interrupts disabled, for the same
reason.
Are you making a comment, or pointing out a flaw in the patch?
AFAICS, the code in question is always under spin_lock_irqsave()
Jeff
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