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From: Christoph Hellwig <hch@infradead.org>
To: Ira Weiny <ira.weiny@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH V10 33/44] kmap: Make kmap work for devmap protected pages
Date: Wed, 18 May 2022 00:33:44 -0700	[thread overview]
Message-ID: <YoShWMGVj9ZJbWqT@infradead.org> (raw)
In-Reply-To: <YoQl3yLa4iDCjicO@iweiny-desk3>

On Tue, May 17, 2022 at 03:46:55PM -0700, Ira Weiny wrote:
> Ok there is a trade off here which I'm not sure is a good idea.
> 
> In order to make kmap faster I carefully placed the devmap_protected() call
> completely inline.[1]  This specifically checks the PGMAP_PROTECTION flag in
> dev_pagemap.[1]
> 
> I see only 2 ways of not including memremap.h in highmem-internal.h.
> 
> 1) Make this check a function call and place it in memremap.c
> 2) Move struct dev_pagemap (and it's dependencies) to another header.
> 
> Number 2 negates any positive effect of splitting the header file.
> 
> Number 1 is going to force some overhead on all ZONE_DEVICE pages if PMEM is in
> the system.
> 
> Do you think the extra run time overhead is a reasonable trade off to
> eliminating the header?

Well, given how big these devmap helpes are it seems like they should be
out of line anyway due to the code size impact.  It would be great to
compare the code size for the cases of:

 1) baseline kernel
 2) devmap protection inline
 3) devmap protection out of line

And maybe you need to add linux-mm and Thomas to get a few more
opinions.

  reply	other threads:[~2022-05-18  7:33 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-19 17:06 [PATCH V10 00/44] PKS/PMEM: Add Stray Write Protection ira.weiny
2022-04-19 17:06 ` [PATCH V10 01/44] Documentation/protection-keys: Clean up documentation for User Space pkeys ira.weiny
2022-06-07 23:09   ` [tip: x86/mm] " tip-bot2 for Ira Weiny
2022-04-19 17:06 ` [PATCH V10 02/44] x86/pkeys: Clarify PKRU_AD_KEY macro ira.weiny
2022-06-07 23:09   ` [tip: x86/mm] " tip-bot2 for Ira Weiny
2022-04-19 17:06 ` [PATCH V10 03/44] x86/pkeys: Make PKRU macros generic ira.weiny
2022-04-19 17:06 ` [PATCH V10 04/44] x86/fpu: Refactor arch_set_user_pkey_access() ira.weiny
2022-04-19 17:06 ` [PATCH V10 05/44] mm/pkeys: Add Kconfig options for PKS ira.weiny
2022-04-19 17:06 ` [PATCH V10 06/44] x86/pkeys: Add PKS CPU feature bit ira.weiny
2022-04-19 17:06 ` [PATCH V10 07/44] x86/fault: Adjust WARN_ON for pkey fault ira.weiny
2022-04-19 17:06 ` [PATCH V10 08/44] Documentation/pkeys: Add initial PKS documentation ira.weiny
2022-05-09 22:03   ` Kees Cook
2022-05-10 17:18     ` Ira Weiny
2022-05-10 20:17       ` Kees Cook
2022-04-19 17:06 ` [PATCH V10 09/44] mm/pkeys: Provide for PKS key allocation ira.weiny
2022-04-19 17:06 ` [PATCH V10 10/44] x86/pkeys: Enable PKS on cpus which support it ira.weiny
2022-04-19 17:06 ` [PATCH V10 11/44] mm/pkeys: Define PKS page table macros ira.weiny
2022-04-19 17:06 ` [PATCH V10 12/44] x86/pkeys: Introduce pks_write_pkrs() ira.weiny
2022-04-19 17:06 ` [PATCH V10 13/44] x86/pkeys: Preserve the PKS MSR on context switch ira.weiny
2022-04-19 17:06 ` [PATCH V10 14/44] mm/pkeys: Introduce pks_set_readwrite() ira.weiny
2022-05-09 21:38   ` Kees Cook
2022-05-10 21:33     ` Ira Weiny
2022-05-10 22:08       ` Kees Cook
2022-05-10 22:26         ` Edgecombe, Rick P
2022-05-11  3:15           ` Kees Cook
2022-05-11 17:59             ` Ira Weiny
2022-04-19 17:06 ` [PATCH V10 15/44] mm/pkeys: Introduce pks_set_noaccess() ira.weiny
2022-04-19 17:06 ` [PATCH V10 16/44] mm/pkeys: Introduce PKS fault callbacks ira.weiny
2022-04-19 17:06 ` [PATCH V10 17/44] x86/entry: Add auxiliary pt_regs space ira.weiny
2022-04-19 17:06 ` [PATCH V10 18/44] entry: Pass pt_regs to irqentry_exit_cond_resched() ira.weiny
2022-04-19 17:06 ` [PATCH V10 19/44] entry: Add calls for save/restore auxiliary pt_regs ira.weiny
2022-04-19 17:06 ` [PATCH V10 20/44] x86/entry: Define arch_{save|restore}_auxiliary_pt_regs() ira.weiny
2022-04-19 17:06 ` [PATCH V10 21/44] x86/pkeys: Preserve PKRS MSR across exceptions ira.weiny
2022-04-19 17:06 ` [PATCH V10 22/44] x86/fault: Print PKS MSR on fault ira.weiny
2022-04-19 17:06 ` [PATCH V10 23/44] mm/pkeys: Introduce pks_update_exception() ira.weiny
2022-04-19 17:06 ` [PATCH V10 24/44] mm/pkeys: Add pks_available() ira.weiny
2022-04-19 17:06 ` [PATCH V10 25/44] memremap_pages: Add Kconfig for DEVMAP_ACCESS_PROTECTION ira.weiny
2022-04-19 17:06 ` [PATCH V10 26/44] memremap_pages: Introduce pgmap_protection_available() ira.weiny
2022-04-19 17:06 ` [PATCH V10 27/44] memremap_pages: Introduce a PGMAP_PROTECTION flag ira.weiny
2022-04-19 17:06 ` [PATCH V10 28/44] memremap_pages: Introduce devmap_protected() ira.weiny
2022-04-19 17:06 ` [PATCH V10 29/44] memremap_pages: Reserve a PKS pkey for eventual use by PMEM ira.weiny
2022-04-19 17:06 ` [PATCH V10 30/44] memremap_pages: Set PKS pkey in PTEs if requested ira.weiny
2022-04-19 17:06 ` [PATCH V10 31/44] memremap_pages: Define pgmap_set_{readwrite|noaccess}() calls ira.weiny
2022-04-19 17:06 ` [PATCH V10 32/44] memremap_pages: Add memremap.pks_fault_mode ira.weiny
2022-04-19 17:06 ` [PATCH V10 33/44] kmap: Make kmap work for devmap protected pages ira.weiny
2022-04-28 15:50   ` Christoph Hellwig
2022-05-12  1:25     ` Ira Weiny
2022-05-17 22:46       ` Ira Weiny
2022-05-18  7:33         ` Christoph Hellwig [this message]
2022-05-19 20:29           ` Ira Weiny
2022-04-19 17:06 ` [PATCH V10 34/44] dax: Stray access protection for dax_direct_access() ira.weiny
2022-04-19 17:06 ` [PATCH V10 35/44] nvdimm/pmem: Enable stray access protection ira.weiny
2022-04-19 17:06 ` [PATCH V10 36/44] devdax: " ira.weiny
2022-04-19 17:06 ` [PATCH V10 37/44] mm/pkeys: PKS testing, add initial test code ira.weiny
2022-04-19 17:06 ` [PATCH V10 38/44] x86/selftests: Add test_pks ira.weiny
2022-04-19 17:06 ` [PATCH V10 39/44] mm/pkeys: PKS testing, add a fault call back ira.weiny
2022-04-19 17:06 ` [PATCH V10 40/44] mm/pkeys: PKS testing, add pks_set_*() tests ira.weiny
2022-04-19 17:06 ` [PATCH V10 41/44] mm/pkeys: PKS testing, test context switching ira.weiny
2022-04-19 17:06 ` [PATCH V10 42/44] mm/pkeys: PKS testing, Add exception test ira.weiny
2022-04-19 17:06 ` [PATCH V10 43/44] mm/pkeys: PKS testing, test pks_update_exception() ira.weiny
2022-04-19 17:06 ` [PATCH V10 44/44] mm/pkeys: PKS testing, add test for all keys ira.weiny

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