On Tue, Sep 01, 2020 at 05:58:29PM +0200, Bodo Stroesser wrote: > On 2020-09-01 16:02, Greg KH wrote: > > On Fri, Aug 28, 2020 at 12:03:38PM +0200, Bodo Stroesser wrote: > >> 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. > > > > I don't see such a request, and am confused now. > > > > What exact commits do you want backported, and to what trees? > > > > thanks, > > > > greg k-h > > > > Sorry for the confusion. > > The subject of the request I mentioned is > "Re: [PATCH v2 0/2] scsi: target: tcmu: fix crashes on ARM" > because it is for the first patch of a small series of two. > > Please backport to kernels 4.19 and 5.4 (it is part of 5.8 from beginning): > 8c4e0f212398 "scsi: target: tcmu: fix size in calls to tcmu_flush_dcache_range" > > Please backport to kernels 4.19, 5.4 and 5.8: > 3c58f737231e "scsi: target: tcmu: Optimize use of flush_dcache_page" > > Backporting to 4.14 or earlier AFAICS would need more work, especially testing. > I don't think that its worth it. Thanks, both now queued up. greg k-h
