Hi,
I'm adding stable@xxxxxxxxxxxxxxx
Once again, this time really adding stable.
On 2020-06-03 04:31, Martin K. Petersen wrote:
On Thu, 28 May 2020 21:31:08 +0200, Bodo Stroesser wrote:
1) If remaining ring space before the end of the ring is
smaller then the next cmd to write, tcmu writes a padding
entry which fills the remaining space at the end of the
ring.
Then tcmu calls tcmu_flush_dcache_range() with the size
of struct tcmu_cmd_entry as data length to flush.
If the space filled by the padding was smaller then
tcmu_cmd_entry, tcmu_flush_dcache_range() is called for
an address range reaching behind the end of the vmalloc'ed
ring.
tcmu_flush_dcache_range() in a loop calls
flush_dcache_page(virt_to_page(start));
for every page being part of the range. On x86 the line is
optimized out by the compiler, as flush_dcache_page() is
empty on x86.
But I assume the above can cause trouble on other
architectures that really have a flush_dcache_page().
For paddings only the header part of an entry is relevant
Due to alignment rules the header always fits in the
remaining space, if padding is needed.
So tcmu_flush_dcache_range() can safely be called with
sizeof(entry->hdr) as the length here.
[...]
Applied to 5.8/scsi-queue, thanks!
[1/1] scsi: target: tcmu: Fix size in calls to tcmu_flush_dcache_range
https://git.kernel.org/mkp/scsi/c/8c4e0f212398
The full commit of this patch is:
8c4e0f212398cdd1eb4310a5981d06a723cdd24f
This patch is the first of four patches that are necessary to run tcmu
on ARM without crash. For details please see
https://bugzilla.kernel.org/show_bug.cgi?id=208045
Upsteam commits of patches 2,3, and 4 are:
2: 3c58f737231e "scsi: target: tcmu: Optimize use of flush_dcache_page"
3: 3145550a7f8b "scsi: target: tcmu: Fix crash in
tcmu_flush_dcache_range on ARM"
4: 5a0c256d96f0 "scsi: target: tcmu: Fix crash on ARM during cmd
completion"
Since patches 3 and 4 already were accepted for 5.8, 5.4, and 4.19, and
I sent a request to add patch 2 about 1 hour ago, please consider adding
this patch to 5.4 and 4.19, because without it tcmu on ARM will still
crash.
Thank you,
Bodo
