On 8/2/23 07:03, Hannes Reinecke wrote: > On 8/2/23 11:41, Christoph Hellwig wrote: >> On Tue, Aug 01, 2023 at 11:31:37PM -0400, Dusty Mabe wrote: >>> We ran a kernel bisect and narrowed it down to offending commit af8b04c6: >>> >>> ``` >>> [root@ibm-p8-kvm-03-guest-02 linux]# git bisect good >>> af8b04c63708fa730c0257084fab91fb2a9cecc4 is the first bad commit >>> commit af8b04c63708fa730c0257084fab91fb2a9cecc4 >>> Author: Christoph Hellwig <hch@xxxxxx> >>> Date: Tue Apr 11 19:14:46 2023 +0200 >>> >>> zram: simplify bvec iteration in __zram_make_request >>> >>> bio_for_each_segment synthetize bvecs that never cross page boundaries, so >>> don't duplicate that work in an inner loop. >> >>> Any ideas on how to fix the problem? >> >> So the interesting cases are: >> >> - ppc64 usually uses 64k page sizes >> - ppc64 is somewhat cache incoherent (compared to say x86) >> >> Let me think of this a bit more. > > Would need to be confirmed first that 64k pages really are in use > (eg we compile ppc64le with 4k page sizes ...). > Dusty? > For which page size did you compile your kernel? For Fedora the configuration is to enable 64k pages with CONFIG_PPC_64K_PAGES=y https://src.fedoraproject.org/rpms/kernel/blob/064c1675a16b4d379b42ab6c3397632ca54ad897/f/kernel-ppc64le-fedora.config#_4791 I used the same configuration when running the git bisect. Dusty
