From: Toshi Kani <toshi.kani@hp.com> To: Borislav Petkov <bp@alien8.de> Cc: hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-nvdimm@lists.01.org, jgross@suse.com, stefan.bader@canonical.com, luto@amacapital.net, hmh@hmh.eng.br, yigal@plexistor.com, konrad.wilk@oracle.com, Elliott@hp.com, mcgrof@suse.com, hch@lst.de Subject: Re: [PATCH v10 11/12] x86, mm, pat: Refactor !pat_enabled handling Date: Fri, 29 May 2015 08:27:08 -0600 [thread overview] Message-ID: <1432909628.23540.40.camel@misato.fc.hp.com> (raw) In-Reply-To: <20150529085842.GA31435@pd.tnic> On Fri, 2015-05-29 at 10:58 +0200, Borislav Petkov wrote: > On Wed, May 27, 2015 at 09:19:03AM -0600, Toshi Kani wrote: > > This patch refactors the !pat_enabled code paths and integrates > > Please refrain from using such empty phrases like "This patch does this > and that" in your commit messages - it is implicitly obvious that it is > "this patch" when one reads it. > > > them into the PAT abstraction code. The PAT table is emulated by > > corresponding to the two cache attribute bits, PWT (Write Through) > > and PCD (Cache Disable). The emulated PAT table is the same as the > > BIOS default setup when the system has PAT but the "nopat" boot > > option is specified. The emulated PAT table is also used when > > MSR_IA32_CR_PAT returns 0 (9d34cfdf4). > > 9d34cfdf4 - what is that thing? A commit message? If so, we quote them > like this: > > 9d34cfdf4796 ("x86: Don't rely on VMWare emulating PAT MSR correctly") > > note the 12 chars length of the commit id. Yes, it refers the commit message above. > > Signed-off-by: Toshi Kani <toshi.kani@hp.com> > > Reviewed-by: Juergen Gross <jgross@suse.com> > > --- > > arch/x86/mm/init.c | 6 ++-- > > arch/x86/mm/iomap_32.c | 12 ++++--- > > arch/x86/mm/ioremap.c | 10 +----- > > arch/x86/mm/pageattr.c | 6 ---- > > arch/x86/mm/pat.c | 77 +++++++++++++++++++++++++++++------------------- > > 5 files changed, 57 insertions(+), 54 deletions(-) > > So I started applying your pile and everything was ok-ish until I came > about this trainwreck. You have a lot of changes in here, the commit > message is certainly lacking sufficient explanation as to why and this > patch is changing stuff which the previous one adds. This !pat_enabled path cleanup was suggested during review and is independent from the WT enablement. So, I thought it'd be better to place it as an additional change on top of the WT set, so that it'd be easier to bisect when there is any issue found in the !pat_enabled path. > So a lot of unnecesary code movement. > > Then you have stuff like this: > > + } else if (!cpu_has_pat && pat_enabled) { > > How can a CPU not have PAT but have it enabled?!? This simply preserves the original error check in the code. This error check makes sure that all CPUs have the PAT feature supported when PAT is enabled. This error can only happen when heterogeneous CPUs are installed/emulated on the system/guest. This check may be paranoid, but this cleanup is not meant to modify such an error check. > So this is not how we do patchsets. > > Please do the cleanups *first*. Do them in small, self-contained changes > explaining *why* you're doing them. > > *Then* add the new functionality, .i.e. the WT. Can you consider the patch 10/12-11/12 as a separate patchset from the WT series? If that is OK, I will resubmit 10/12 (BUG->panic) and 11/12 (commit log update). > Oh, and when you do your next version, do the patches against tip/master > because there are a bunch of changes in the PAT code already. Thanks, -Toshi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
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From: Toshi Kani <toshi.kani@hp.com> To: Borislav Petkov <bp@alien8.de> Cc: hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-nvdimm@ml01.01.org, jgross@suse.com, stefan.bader@canonical.com, luto@amacapital.net, hmh@hmh.eng.br, yigal@plexistor.com, konrad.wilk@oracle.com, Elliott@hp.com, mcgrof@suse.com, hch@lst.de Subject: Re: [PATCH v10 11/12] x86, mm, pat: Refactor !pat_enabled handling Date: Fri, 29 May 2015 08:27:08 -0600 [thread overview] Message-ID: <1432909628.23540.40.camel@misato.fc.hp.com> (raw) In-Reply-To: <20150529085842.GA31435@pd.tnic> On Fri, 2015-05-29 at 10:58 +0200, Borislav Petkov wrote: > On Wed, May 27, 2015 at 09:19:03AM -0600, Toshi Kani wrote: > > This patch refactors the !pat_enabled code paths and integrates > > Please refrain from using such empty phrases like "This patch does this > and that" in your commit messages - it is implicitly obvious that it is > "this patch" when one reads it. > > > them into the PAT abstraction code. The PAT table is emulated by > > corresponding to the two cache attribute bits, PWT (Write Through) > > and PCD (Cache Disable). The emulated PAT table is the same as the > > BIOS default setup when the system has PAT but the "nopat" boot > > option is specified. The emulated PAT table is also used when > > MSR_IA32_CR_PAT returns 0 (9d34cfdf4). > > 9d34cfdf4 - what is that thing? A commit message? If so, we quote them > like this: > > 9d34cfdf4796 ("x86: Don't rely on VMWare emulating PAT MSR correctly") > > note the 12 chars length of the commit id. Yes, it refers the commit message above. > > Signed-off-by: Toshi Kani <toshi.kani@hp.com> > > Reviewed-by: Juergen Gross <jgross@suse.com> > > --- > > arch/x86/mm/init.c | 6 ++-- > > arch/x86/mm/iomap_32.c | 12 ++++--- > > arch/x86/mm/ioremap.c | 10 +----- > > arch/x86/mm/pageattr.c | 6 ---- > > arch/x86/mm/pat.c | 77 +++++++++++++++++++++++++++++------------------- > > 5 files changed, 57 insertions(+), 54 deletions(-) > > So I started applying your pile and everything was ok-ish until I came > about this trainwreck. You have a lot of changes in here, the commit > message is certainly lacking sufficient explanation as to why and this > patch is changing stuff which the previous one adds. This !pat_enabled path cleanup was suggested during review and is independent from the WT enablement. So, I thought it'd be better to place it as an additional change on top of the WT set, so that it'd be easier to bisect when there is any issue found in the !pat_enabled path. > So a lot of unnecesary code movement. > > Then you have stuff like this: > > + } else if (!cpu_has_pat && pat_enabled) { > > How can a CPU not have PAT but have it enabled?!? This simply preserves the original error check in the code. This error check makes sure that all CPUs have the PAT feature supported when PAT is enabled. This error can only happen when heterogeneous CPUs are installed/emulated on the system/guest. This check may be paranoid, but this cleanup is not meant to modify such an error check. > So this is not how we do patchsets. > > Please do the cleanups *first*. Do them in small, self-contained changes > explaining *why* you're doing them. > > *Then* add the new functionality, .i.e. the WT. Can you consider the patch 10/12-11/12 as a separate patchset from the WT series? If that is OK, I will resubmit 10/12 (BUG->panic) and 11/12 (commit log update). > Oh, and when you do your next version, do the patches against tip/master > because there are a bunch of changes in the PAT code already. Thanks, -Toshi
next prev parent reply other threads:[~2015-05-29 14:27 UTC|newest] Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-05-27 15:18 [PATCH v10 0/12] Support Write-Through mapping on x86 Toshi Kani 2015-05-27 15:18 ` Toshi Kani 2015-05-27 15:18 ` [PATCH v10 1/12] x86, mm, pat: Set WT to PA7 slot of PAT MSR Toshi Kani 2015-05-27 15:18 ` Toshi Kani 2015-05-27 15:18 ` [PATCH v10 2/12] x86, mm, pat: Change reserve_memtype() for WT Toshi Kani 2015-05-27 15:18 ` Toshi Kani 2015-05-27 15:18 ` [PATCH v10 3/12] x86, asm: Change is_new_memtype_allowed() " Toshi Kani 2015-05-27 15:18 ` Toshi Kani 2015-05-27 15:18 ` [PATCH v10 4/12] x86, mm, asm-gen: Add ioremap_wt() " Toshi Kani 2015-05-27 15:18 ` Toshi Kani 2015-05-27 15:18 ` [PATCH v10 5/12] arch/*/asm/io.h: Add ioremap_wt() to all architectures Toshi Kani 2015-05-27 15:18 ` Toshi Kani 2015-05-27 15:18 ` [PATCH v10 6/12] video/fbdev, asm/io.h: Remove ioremap_writethrough() Toshi Kani 2015-05-27 15:18 ` Toshi Kani 2015-05-27 15:18 ` [PATCH v10 7/12] x86, mm, pat: Add pgprot_writethrough() for WT Toshi Kani 2015-05-27 15:18 ` Toshi Kani 2015-05-27 15:19 ` [PATCH v10 8/12] x86, mm, asm: Add WT support to set_page_memtype() Toshi Kani 2015-05-27 15:19 ` Toshi Kani 2015-05-27 15:19 ` [PATCH v10 9/12] x86, mm: Add set_memory_wt() for WT Toshi Kani 2015-05-27 15:19 ` Toshi Kani 2015-05-27 15:19 ` [PATCH v10 10/12] x86, mm, pat: Cleanup init flags in pat_init() Toshi Kani 2015-05-27 15:19 ` Toshi Kani 2015-05-29 8:59 ` Borislav Petkov 2015-05-29 8:59 ` Borislav Petkov 2015-05-27 15:19 ` [PATCH v10 11/12] x86, mm, pat: Refactor !pat_enabled handling Toshi Kani 2015-05-27 15:19 ` Toshi Kani 2015-05-29 8:58 ` Borislav Petkov 2015-05-29 8:58 ` Borislav Petkov 2015-05-29 14:27 ` Toshi Kani [this message] 2015-05-29 14:27 ` Toshi Kani 2015-05-29 15:13 ` Borislav Petkov 2015-05-29 15:13 ` Borislav Petkov 2015-05-29 15:17 ` Toshi Kani 2015-05-29 15:17 ` Toshi Kani 2015-05-27 15:19 ` [PATCH v10 12/12] drivers/block/pmem: Map NVDIMM with ioremap_wt() Toshi Kani 2015-05-27 15:19 ` Toshi Kani 2015-05-29 9:11 ` Borislav Petkov 2015-05-29 9:11 ` Borislav Petkov 2015-05-29 14:43 ` Dan Williams 2015-05-29 14:43 ` Dan Williams 2015-05-29 15:03 ` Toshi Kani 2015-05-29 15:03 ` Toshi Kani 2015-05-29 15:03 ` Toshi Kani 2015-05-29 18:19 ` Dan Williams 2015-05-29 18:19 ` Dan Williams 2015-05-29 18:32 ` Toshi Kani 2015-05-29 18:32 ` Toshi Kani 2015-05-29 18:32 ` Toshi Kani 2015-05-29 19:34 ` Dan Williams 2015-05-29 19:34 ` Dan Williams 2015-05-29 20:10 ` Toshi Kani 2015-05-29 20:10 ` Toshi Kani 2015-05-29 18:34 ` Andy Lutomirski 2015-05-29 18:34 ` Andy Lutomirski 2015-05-29 19:32 ` Dan Williams 2015-05-29 19:32 ` Dan Williams 2015-05-29 21:29 ` Elliott, Robert (Server Storage) 2015-05-29 21:29 ` Elliott, Robert (Server Storage) 2015-05-29 21:29 ` Elliott, Robert (Server Storage) 2015-05-29 21:46 ` Andy Lutomirski 2015-05-29 21:46 ` Andy Lutomirski 2015-05-29 22:24 ` Elliott, Robert (Server Storage) 2015-05-29 22:24 ` Elliott, Robert (Server Storage) 2015-05-29 22:24 ` Elliott, Robert (Server Storage) 2015-05-29 22:32 ` H. Peter Anvin 2015-05-29 22:32 ` H. Peter Anvin 2015-06-01 8:58 ` Ingo Molnar 2015-06-01 8:58 ` Ingo Molnar 2015-06-01 17:10 ` Andy Lutomirski 2015-06-01 17:10 ` Andy Lutomirski
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