This is a note to let you know that I've just added the patch titled
s390/dasd: Fix zero write for FBA devices
to the 5.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-dasd-fix-zero-write-for-fba-devices.patch
and it can be found in the queue-5.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 709192d531e5b0a91f20aa14abfe2fc27ddd47af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20H=C3=B6ppner?= <hoeppner@xxxxxxxxxxxxx>
Date: Mon, 14 Sep 2020 13:56:47 +0200
Subject: s390/dasd: Fix zero write for FBA devices
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From: Jan Höppner <hoeppner@xxxxxxxxxxxxx>
commit 709192d531e5b0a91f20aa14abfe2fc27ddd47af upstream.
A discard request that writes zeros using the global kernel internal
ZERO_PAGE will fail for machines with more than 2GB of memory due to the
location of the ZERO_PAGE.
Fix this by using a driver owned global zero page allocated with GFP_DMA
flag set.
Fixes: 28b841b3a7cb ("s390/dasd: Add discard support for FBA devices")
Signed-off-by: Jan Höppner <hoeppner@xxxxxxxxxxxxx>
Reviewed-by: Stefan Haberland <sth@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 4.14+
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/s390/block/dasd_fba.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
--- a/drivers/s390/block/dasd_fba.c
+++ b/drivers/s390/block/dasd_fba.c
@@ -40,6 +40,7 @@
MODULE_LICENSE("GPL");
static struct dasd_discipline dasd_fba_discipline;
+static void *dasd_fba_zero_page;
struct dasd_fba_private {
struct dasd_fba_characteristics rdc_data;
@@ -270,7 +271,7 @@ static void ccw_write_zero(struct ccw1 *
ccw->cmd_code = DASD_FBA_CCW_WRITE;
ccw->flags |= CCW_FLAG_SLI;
ccw->count = count;
- ccw->cda = (__u32) (addr_t) page_to_phys(ZERO_PAGE(0));
+ ccw->cda = (__u32) (addr_t) dasd_fba_zero_page;
}
/*
@@ -830,6 +831,11 @@ dasd_fba_init(void)
int ret;
ASCEBC(dasd_fba_discipline.ebcname, 4);
+
+ dasd_fba_zero_page = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
+ if (!dasd_fba_zero_page)
+ return -ENOMEM;
+
ret = ccw_driver_register(&dasd_fba_driver);
if (!ret)
wait_for_device_probe();
@@ -841,6 +847,7 @@ static void __exit
dasd_fba_cleanup(void)
{
ccw_driver_unregister(&dasd_fba_driver);
+ free_page((unsigned long)dasd_fba_zero_page);
}
module_init(dasd_fba_init);
Patches currently in stable-queue which might be from hoeppner@xxxxxxxxxxxxx are
queue-5.8/s390-dasd-fix-zero-write-for-fba-devices.patch
