Hi, I'm adding stable@xxxxxxxxxxxxxxx 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
