Re: [PATCH v4 5/5] pagemap: add mmap-exclusive bit for marking pages mapped only here

2015-07-24 Thread Mark Williamson
Reviewed-by: Mark Williamson On Tue, Jul 21, 2015 at 9:17 AM, Naoya Horiguchi wrote: > On Tue, Jul 14, 2015 at 06:37:49PM +0300, Konstantin Khlebnikov wrote: >> This patch sets bit 56 in pagemap if this page is mapped only once. >> It allows to detect exclusively used pages witho

Re: [PATCH v4 3/5] pagemap: rework hugetlb and thp report

2015-07-24 Thread Mark Williamson
(my review on this patch comes with the caveat that the specifics of hugetlb / thp are a bit outside my experience) On Fri, Jul 24, 2015 at 7:17 PM, Mark Williamson wrote: > Reviewed-by: Mark Williamson > > On Tue, Jul 21, 2015 at 9:43 AM, Konstantin Khlebnikov > wrote: >&

Re: [PATCH v4 4/5] pagemap: hide physical addresses from non-privileged users

2015-07-24 Thread Mark Williamson
Reviewed-by: Mark Williamson On Tue, Jul 21, 2015 at 9:39 AM, Konstantin Khlebnikov wrote: > On Tue, Jul 21, 2015 at 11:11 AM, Naoya Horiguchi > wrote: >> On Tue, Jul 14, 2015 at 06:37:47PM +0300, Konstantin Khlebnikov wrote: >>> This patch makes pagemap readable for n

Re: [PATCH v4 3/5] pagemap: rework hugetlb and thp report

2015-07-24 Thread Mark Williamson
Reviewed-by: Mark Williamson On Tue, Jul 21, 2015 at 9:43 AM, Konstantin Khlebnikov wrote: > On Tue, Jul 21, 2015 at 11:00 AM, Naoya Horiguchi > wrote: >> On Tue, Jul 14, 2015 at 06:37:39PM +0300, Konstantin Khlebnikov wrote: >>> This patch moves pmd dissection out of

Re: [PATCH v4 1/5] pagemap: check permissions and capabilities at open time

2015-07-24 Thread Mark Williamson
(within the limits of my understanding of the mm code) Reviewed-by: Mark Williamson On Tue, Jul 21, 2015 at 9:06 AM, Naoya Horiguchi wrote: > On Tue, Jul 14, 2015 at 06:37:35PM +0300, Konstantin Khlebnikov wrote: >> This patch moves permission checks from pagemap_read() into pag

Re: [PATCHSET v4 0/5] pagemap: make useable for non-privilege users

2015-07-24 Thread Mark Williamson
Hi Konstantin, Thank you for the further update - I tested this patchset against our code and it allows our software to work correctly (with minor userland changes, as before). I'll follow up with review messages but there aren't really any concerns that I can see. Cheers, Mark On Tue, Jul 14,

Re: [PATCH v4 3/5] pagemap: rework hugetlb and thp report

2015-07-24 Thread Mark Williamson
Reviewed-by: Mark Williamson mwilliam...@undo-software.com On Tue, Jul 21, 2015 at 9:43 AM, Konstantin Khlebnikov koc...@gmail.com wrote: On Tue, Jul 21, 2015 at 11:00 AM, Naoya Horiguchi n-horigu...@ah.jp.nec.com wrote: On Tue, Jul 14, 2015 at 06:37:39PM +0300, Konstantin Khlebnikov wrote

Re: [PATCHSET v4 0/5] pagemap: make useable for non-privilege users

2015-07-24 Thread Mark Williamson
Hi Konstantin, Thank you for the further update - I tested this patchset against our code and it allows our software to work correctly (with minor userland changes, as before). I'll follow up with review messages but there aren't really any concerns that I can see. Cheers, Mark On Tue, Jul 14,

Re: [PATCH v4 1/5] pagemap: check permissions and capabilities at open time

2015-07-24 Thread Mark Williamson
(within the limits of my understanding of the mm code) Reviewed-by: Mark Williamson mwilliam...@undo-software.com On Tue, Jul 21, 2015 at 9:06 AM, Naoya Horiguchi n-horigu...@ah.jp.nec.com wrote: On Tue, Jul 14, 2015 at 06:37:35PM +0300, Konstantin Khlebnikov wrote: This patch moves permission

Re: [PATCH v4 5/5] pagemap: add mmap-exclusive bit for marking pages mapped only here

2015-07-24 Thread Mark Williamson
Reviewed-by: Mark Williamson mwilliam...@undo-software.com On Tue, Jul 21, 2015 at 9:17 AM, Naoya Horiguchi n-horigu...@ah.jp.nec.com wrote: On Tue, Jul 14, 2015 at 06:37:49PM +0300, Konstantin Khlebnikov wrote: This patch sets bit 56 in pagemap if this page is mapped only once. It allows

Re: [PATCH v4 4/5] pagemap: hide physical addresses from non-privileged users

2015-07-24 Thread Mark Williamson
Reviewed-by: Mark Williamson mwilliam...@undo-software.com On Tue, Jul 21, 2015 at 9:39 AM, Konstantin Khlebnikov koc...@gmail.com wrote: On Tue, Jul 21, 2015 at 11:11 AM, Naoya Horiguchi n-horigu...@ah.jp.nec.com wrote: On Tue, Jul 14, 2015 at 06:37:47PM +0300, Konstantin Khlebnikov wrote

Re: [PATCH v4 3/5] pagemap: rework hugetlb and thp report

2015-07-24 Thread Mark Williamson
(my review on this patch comes with the caveat that the specifics of hugetlb / thp are a bit outside my experience) On Fri, Jul 24, 2015 at 7:17 PM, Mark Williamson mwilliam...@undo-software.com wrote: Reviewed-by: Mark Williamson mwilliam...@undo-software.com On Tue, Jul 21, 2015 at 9:43 AM

Re: [PATCH v4] pagemap: switch to the new format and do some cleanup

2015-06-15 Thread Mark Williamson
Thanks! No outstanding issues with the patchset, from our side. Reviewed-by: mwilliam...@undo-software.com On Mon, Jun 15, 2015 at 6:56 AM, Konstantin Khlebnikov wrote: > From: Konstantin Khlebnikov > > This patch removes page-shift bits (scheduled to remove since 3.11) and > completes

Re: [PATCH v4] pagemap: switch to the new format and do some cleanup

2015-06-15 Thread Mark Williamson
Thanks! No outstanding issues with the patchset, from our side. Reviewed-by: mwilliam...@undo-software.com On Mon, Jun 15, 2015 at 6:56 AM, Konstantin Khlebnikov koc...@gmail.com wrote: From: Konstantin Khlebnikov khlebni...@yandex-team.ru This patch removes page-shift bits (scheduled to

Re: [PATCHSET v3 0/4] pagemap: make useable for non-privilege users

2015-06-12 Thread Mark Williamson
Hi Konstantin, Thanks very much for your help on this. >From our side, I've tested our application against a patched kernel and I confirm that the functionality can replace what we lost when PFNs were removed from /proc/PID/pagemap. This addresses the functionality regression from our PoV (just

Re: [PATCH v3 4/4] pagemap: switch to the new format and do some cleanup

2015-06-12 Thread Mark Williamson
One tiny nitpick / typo, inline below - functionally, this looks good from our side... Reviewed-by: mwilliam...@undo-software.com Tested-by: mwilliam...@undo-software.com On Tue, Jun 9, 2015 at 9:00 PM, Konstantin Khlebnikov wrote: > From: Konstantin Khlebnikov <...snip...> > -#define

Re: [PATCH v3 3/4] pagemap: hide physical addresses from non-privileged users

2015-06-12 Thread Mark Williamson
This looks good from our side - thanks! Reviewed-by: mwilliam...@undo-software.com Tested-by: mwilliam...@undo-software.com On Tue, Jun 9, 2015 at 9:00 PM, Konstantin Khlebnikov wrote: > From: Konstantin Khlebnikov > > This patch makes pagemap readable for normal users back but hides physical

Re: [PATCH v3 2/4] pagemap: add mmap-exclusive bit for marking pages mapped only here

2015-06-12 Thread Mark Williamson
This looks good from our side - thanks! Reviewed-by: mwilliam...@undo-software.com Tested-by: mwilliam...@undo-software.com On Tue, Jun 9, 2015 at 9:00 PM, Konstantin Khlebnikov wrote: > From: Konstantin Khlebnikov > > This patch sets bit 56 in pagemap if this page is mapped only once. > It

Re: [PATCH v3 1/4] pagemap: check permissions and capabilities at open time

2015-06-12 Thread Mark Williamson
This looks good from our side - thanks! Reviewed-by: mwilliam...@undo-software.com Tested-by: mwilliam...@undo-software.com On Tue, Jun 9, 2015 at 9:00 PM, Konstantin Khlebnikov wrote: > From: Konstantin Khlebnikov > > This patch moves permission checks from pagemap_read() into pagemap_open().

Re: [PATCH v3 2/4] pagemap: add mmap-exclusive bit for marking pages mapped only here

2015-06-12 Thread Mark Williamson
This looks good from our side - thanks! Reviewed-by: mwilliam...@undo-software.com Tested-by: mwilliam...@undo-software.com On Tue, Jun 9, 2015 at 9:00 PM, Konstantin Khlebnikov koc...@gmail.com wrote: From: Konstantin Khlebnikov khlebni...@yandex-team.ru This patch sets bit 56 in pagemap if

Re: [PATCH v3 1/4] pagemap: check permissions and capabilities at open time

2015-06-12 Thread Mark Williamson
This looks good from our side - thanks! Reviewed-by: mwilliam...@undo-software.com Tested-by: mwilliam...@undo-software.com On Tue, Jun 9, 2015 at 9:00 PM, Konstantin Khlebnikov koc...@gmail.com wrote: From: Konstantin Khlebnikov khlebni...@yandex-team.ru This patch moves permission checks

Re: [PATCH v3 3/4] pagemap: hide physical addresses from non-privileged users

2015-06-12 Thread Mark Williamson
This looks good from our side - thanks! Reviewed-by: mwilliam...@undo-software.com Tested-by: mwilliam...@undo-software.com On Tue, Jun 9, 2015 at 9:00 PM, Konstantin Khlebnikov koc...@gmail.com wrote: From: Konstantin Khlebnikov khlebni...@yandex-team.ru This patch makes pagemap readable for

Re: [PATCH v3 4/4] pagemap: switch to the new format and do some cleanup

2015-06-12 Thread Mark Williamson
One tiny nitpick / typo, inline below - functionally, this looks good from our side... Reviewed-by: mwilliam...@undo-software.com Tested-by: mwilliam...@undo-software.com On Tue, Jun 9, 2015 at 9:00 PM, Konstantin Khlebnikov koc...@gmail.com wrote: From: Konstantin Khlebnikov

Re: [PATCHSET v3 0/4] pagemap: make useable for non-privilege users

2015-06-12 Thread Mark Williamson
Hi Konstantin, Thanks very much for your help on this. From our side, I've tested our application against a patched kernel and I confirm that the functionality can replace what we lost when PFNs were removed from /proc/PID/pagemap. This addresses the functionality regression from our PoV (just

Re: [PATCH RFC 0/3] pagemap: make useable for non-privilege users

2015-06-08 Thread Mark Williamson
On Thu, May 14, 2015 at 7:40 PM, Mark Williamson wrote: > Hi Konstantin, > > I modified our code to check for the map-exclusive flag where it used > to compare pageframe numbers. First tests look pretty promising, so > this patch looks like a viable approach for us. > > Is ther

Re: [PATCH RFC 0/3] pagemap: make useable for non-privilege users

2015-06-08 Thread Mark Williamson
On Thu, May 14, 2015 at 7:40 PM, Mark Williamson mwilliam...@undo-software.com wrote: Hi Konstantin, I modified our code to check for the map-exclusive flag where it used to compare pageframe numbers. First tests look pretty promising, so this patch looks like a viable approach for us

Re: [PATCH v2 1/3] pagemap: add mmap-exclusive bit for marking pages mapped only here

2015-05-14 Thread Mark Williamson
Hi Konstantin, On Wed, May 13, 2015 at 11:51 AM, Konstantin Khlebnikov wrote: > On 12.05.2015 15:05, Mark Williamson wrote: >> 1. I was hoping we'd be able to backport a compatible fix to older >> kernels that might adopt the pagemap permissions change. Using the V2 >> f

Re: [PATCH RFC 0/3] pagemap: make useable for non-privilege users

2015-05-14 Thread Mark Williamson
, Mark Williamson wrote: > Hi Konstantin, > > Thanks very much for continuing to look at this! It's very much > appreciated. I've been investigating from our end but got caught up > in some gnarly details of our pagemap-consuming code. > > I like the approach and it seems

Re: [PATCH RFC 0/3] pagemap: make useable for non-privilege users

2015-05-14 Thread Mark Williamson
, Mark Williamson mwilliam...@undo-software.com wrote: Hi Konstantin, Thanks very much for continuing to look at this! It's very much appreciated. I've been investigating from our end but got caught up in some gnarly details of our pagemap-consuming code. I like the approach and it seems like

Re: [PATCH v2 1/3] pagemap: add mmap-exclusive bit for marking pages mapped only here

2015-05-14 Thread Mark Williamson
Hi Konstantin, On Wed, May 13, 2015 at 11:51 AM, Konstantin Khlebnikov khlebni...@yandex-team.ru wrote: On 12.05.2015 15:05, Mark Williamson wrote: snip 1. I was hoping we'd be able to backport a compatible fix to older kernels that might adopt the pagemap permissions change. Using the V2

Re: [PATCH v2 1/3] pagemap: add mmap-exclusive bit for marking pages mapped only here

2015-05-12 Thread Mark Williamson
Hi Konstantin, I hope you won't mind me thinking out loud here on the idea of adding a flag to the v2 pagemap fields... From a kernel PoV, I agree that this seems like the cleanest approach. However, with my application developer hat on: 1. I was hoping we'd be able to backport a compatible

Re: [PATCH v2 2/3] pagemap: hide physical addresses from non-privileged users

2015-05-12 Thread Mark Williamson
Hi Konstantin, Comments inline... On Tue, May 12, 2015 at 10:43 AM, Konstantin Khlebnikov wrote: > This patch makes pagemap readable for normal users back but hides physical > addresses from them. For some use cases PFN isn't required at all: flags > give information about presence, page type

Re: [PATCH RFC 0/3] pagemap: make useable for non-privilege users

2015-05-12 Thread Mark Williamson
Hi Konstantin, Thanks very much for continuing to look at this! It's very much appreciated. I've been investigating from our end but got caught up in some gnarly details of our pagemap-consuming code. I like the approach and it seems like the information you're exposing will be useful for our

Re: [PATCH RFC 0/3] pagemap: make useable for non-privilege users

2015-05-12 Thread Mark Williamson
Hi Konstantin, Thanks very much for continuing to look at this! It's very much appreciated. I've been investigating from our end but got caught up in some gnarly details of our pagemap-consuming code. I like the approach and it seems like the information you're exposing will be useful for our

Re: [PATCH v2 1/3] pagemap: add mmap-exclusive bit for marking pages mapped only here

2015-05-12 Thread Mark Williamson
Hi Konstantin, I hope you won't mind me thinking out loud here on the idea of adding a flag to the v2 pagemap fields... From a kernel PoV, I agree that this seems like the cleanest approach. However, with my application developer hat on: 1. I was hoping we'd be able to backport a compatible

Re: [PATCH v2 2/3] pagemap: hide physical addresses from non-privileged users

2015-05-12 Thread Mark Williamson
Hi Konstantin, Comments inline... On Tue, May 12, 2015 at 10:43 AM, Konstantin Khlebnikov khlebni...@yandex-team.ru wrote: This patch makes pagemap readable for normal users back but hides physical addresses from them. For some use cases PFN isn't required at all: flags give information about

Re: Regression: Requiring CAP_SYS_ADMIN for /proc//pagemap causes application-level breakage

2015-04-30 Thread Mark Williamson
>> Something like this (see patch in attachment) > > THP is not covered. > > Any comments on kcmp() idea? It seems like a modified kcmp() would also be a valid approach but, as you noted, probably speed-limited for our purposes. As you say, there is the option of a vector-oriented equivalent.

Re: Regression: Requiring CAP_SYS_ADMIN for /proc//pagemap causes application-level breakage

2015-04-30 Thread Mark Williamson
Hi all, On Thu, Apr 30, 2015 at 2:11 PM, Konstantin Khlebnikov wrote: > On Thu, Apr 30, 2015 at 2:43 PM, Konstantin Khlebnikov > wrote: >> What about exposing shared/exclusive bit in pagemap == 1 if >> page_mapcount() > 1, otherwise 0 (or vise versa). >> >> Seems like this should work for

Re: Regression: Requiring CAP_SYS_ADMIN for /proc//pagemap causes application-level breakage

2015-04-30 Thread Mark Williamson
On Wed, Apr 29, 2015 at 10:02 PM, Linus Torvalds wrote: > On Wed, Apr 29, 2015 at 1:44 PM, Konstantin Khlebnikov > wrote: >> >> This's no longer true. After recent fixes for "anon_vma endless growing" new >> vma >> might reuse old anon_vma from grandparent vma. > > Oh well. I guess that was

Re: Regression: Requiring CAP_SYS_ADMIN for /proc/pid/pagemap causes application-level breakage

2015-04-30 Thread Mark Williamson
On Wed, Apr 29, 2015 at 10:02 PM, Linus Torvalds torva...@linux-foundation.org wrote: On Wed, Apr 29, 2015 at 1:44 PM, Konstantin Khlebnikov koc...@gmail.com wrote: This's no longer true. After recent fixes for anon_vma endless growing new vma might reuse old anon_vma from grandparent vma.

Re: Regression: Requiring CAP_SYS_ADMIN for /proc/pid/pagemap causes application-level breakage

2015-04-30 Thread Mark Williamson
Hi all, On Thu, Apr 30, 2015 at 2:11 PM, Konstantin Khlebnikov koc...@gmail.com wrote: On Thu, Apr 30, 2015 at 2:43 PM, Konstantin Khlebnikov koc...@gmail.com wrote: What about exposing shared/exclusive bit in pagemap == 1 if page_mapcount() 1, otherwise 0 (or vise versa). Seems like this

Re: Regression: Requiring CAP_SYS_ADMIN for /proc/pid/pagemap causes application-level breakage

2015-04-30 Thread Mark Williamson
Something like this (see patch in attachment) THP is not covered. Any comments on kcmp() idea? It seems like a modified kcmp() would also be a valid approach but, as you noted, probably speed-limited for our purposes. As you say, there is the option of a vector-oriented equivalent. It

Re: Regression: Requiring CAP_SYS_ADMIN for /proc//pagemap causes application-level breakage

2015-04-29 Thread Mark Williamson
Hi, On Wed, Apr 29, 2015 at 8:36 PM, Kirill A. Shutemov wrote: > On Wed, Apr 29, 2015 at 07:44:57PM +0100, Mark Williamson wrote: >> Hi all, ... snip ... >> For context, we were previously using pagemap as a cross-platform way >> to get soft-dirty-like functionality. Spec

Re: Regression: Requiring CAP_SYS_ADMIN for /proc//pagemap causes application-level breakage

2015-04-29 Thread Mark Williamson
Hi again, On Wed, Apr 29, 2015 at 7:44 PM, Mark Williamson wrote: > We've been investigating further and found a snag with the PFN-hiding > approach discussed last week - looks like it won't be enough on all > the architectures we support. Our product runs on x86_32, x86_64 and > A

Re: Regression: Requiring CAP_SYS_ADMIN for /proc//pagemap causes application-level breakage

2015-04-29 Thread Mark Williamson
post another thread for. On Fri, Apr 24, 2015 at 5:43 PM, Mark Williamson wrote: > Hi Mark, > > On Fri, Apr 24, 2015 at 4:26 PM, Mark Seaborn wrote: >> I'm curious, what do you use the physical page addresses for? >> >> Since you pointed to http://undo-software.com, whi

Re: Regression: Requiring CAP_SYS_ADMIN for /proc//pagemap causes application-level breakage

2015-04-29 Thread Mark Williamson
Hi Andy, On Fri, Apr 24, 2015 at 5:10 PM, Andy Lutomirski wrote: > Even though I've been accused (correctly?) of suggesting that, I'm not > sure I like it anymore. Suppose I map some anonymous memory, learn > its (scrambled) pfn, then unmap it and remap a setuid file. Now I can > tell whether

Re: Regression: Requiring CAP_SYS_ADMIN for /proc/pid/pagemap causes application-level breakage

2015-04-29 Thread Mark Williamson
Hi again, On Wed, Apr 29, 2015 at 7:44 PM, Mark Williamson mwilliam...@undo-software.com wrote: We've been investigating further and found a snag with the PFN-hiding approach discussed last week - looks like it won't be enough on all the architectures we support. Our product runs on x86_32

Re: Regression: Requiring CAP_SYS_ADMIN for /proc/pid/pagemap causes application-level breakage

2015-04-29 Thread Mark Williamson
for. On Fri, Apr 24, 2015 at 5:43 PM, Mark Williamson mwilliam...@undo-software.com wrote: Hi Mark, On Fri, Apr 24, 2015 at 4:26 PM, Mark Seaborn mseab...@chromium.org wrote: I'm curious, what do you use the physical page addresses for? Since you pointed to http://undo-software.com, which talks

Re: Regression: Requiring CAP_SYS_ADMIN for /proc/pid/pagemap causes application-level breakage

2015-04-29 Thread Mark Williamson
Hi, On Wed, Apr 29, 2015 at 8:36 PM, Kirill A. Shutemov kir...@shutemov.name wrote: On Wed, Apr 29, 2015 at 07:44:57PM +0100, Mark Williamson wrote: Hi all, ... snip ... For context, we were previously using pagemap as a cross-platform way to get soft-dirty-like functionality. Specifically

Re: Regression: Requiring CAP_SYS_ADMIN for /proc/pid/pagemap causes application-level breakage

2015-04-29 Thread Mark Williamson
Hi Andy, On Fri, Apr 24, 2015 at 5:10 PM, Andy Lutomirski l...@amacapital.net wrote: Even though I've been accused (correctly?) of suggesting that, I'm not sure I like it anymore. Suppose I map some anonymous memory, learn its (scrambled) pfn, then unmap it and remap a setuid file. Now I can

Re: Regression: Requiring CAP_SYS_ADMIN for /proc//pagemap causes application-level breakage

2015-04-24 Thread Mark Williamson
Hi Linus, Thanks for responding so quickly! On Fri, Apr 24, 2015 at 5:08 PM, Linus Torvalds wrote: > So the one exception to the regression rule is "security fixes", but > even for security fixes we do try to be as reasonable as humanly > possible to make them not break things. Understood -

Re: Regression: Requiring CAP_SYS_ADMIN for /proc//pagemap causes application-level breakage

2015-04-24 Thread Mark Williamson
Hi Mark, On Fri, Apr 24, 2015 at 4:26 PM, Mark Seaborn wrote: > I'm curious, what do you use the physical page addresses for? > > Since you pointed to http://undo-software.com, which talks about > reversible debugging tools, I can guess you would use the soft-dirty > flag to implement

Regression: Requiring CAP_SYS_ADMIN for /proc//pagemap causes application-level breakage

2015-04-24 Thread Mark Williamson
e physical pageframe addresses zeroed. Would this be an acceptable approach? Thank you, Mark Williamson --- Undo Software - http://undo-software.com/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More maj

Re: Regression: Requiring CAP_SYS_ADMIN for /proc/pid/pagemap causes application-level breakage

2015-04-24 Thread Mark Williamson
Hi Linus, Thanks for responding so quickly! On Fri, Apr 24, 2015 at 5:08 PM, Linus Torvalds torva...@linux-foundation.org wrote: So the one exception to the regression rule is security fixes, but even for security fixes we do try to be as reasonable as humanly possible to make them not break

Re: Regression: Requiring CAP_SYS_ADMIN for /proc/pid/pagemap causes application-level breakage

2015-04-24 Thread Mark Williamson
Hi Mark, On Fri, Apr 24, 2015 at 4:26 PM, Mark Seaborn mseab...@chromium.org wrote: I'm curious, what do you use the physical page addresses for? Since you pointed to http://undo-software.com, which talks about reversible debugging tools, I can guess you would use the soft-dirty flag to

Regression: Requiring CAP_SYS_ADMIN for /proc/pid/pagemap causes application-level breakage

2015-04-24 Thread Mark Williamson
up with a patch that provides unprivileged access to /proc/PID/pagemap with the physical pageframe addresses zeroed. Would this be an acceptable approach? Thank you, Mark Williamson --- Undo Software - http://undo-software.com/ -- To unsubscribe from this list: send the line unsubscribe linux

Re: [RFC 12/26] ext2 white-out support

2007-07-31 Thread Mark Williamson
> Really the only sane way of keeping track of whiteouts seems some external > store. We did an experiment with Unionfs, and moving the whiteout handling > to effectively a "library" that did all the dirty work cleaned up the code > considerably [2,3]. What about keeping track of whiteouts in a

Re: [RFC 12/26] ext2 white-out support

2007-07-31 Thread Mark Williamson
Really the only sane way of keeping track of whiteouts seems some external store. We did an experiment with Unionfs, and moving the whiteout handling to effectively a library that did all the dirty work cleaned up the code considerably [2,3]. What about keeping track of whiteouts in a special

Re: Versioning file system

2007-06-16 Thread Mark Williamson
> I reviewed your sample implementation, and it appears to infringe 3 > patents already.You should do some research on this. Are you able to tell us which areas of the code infringe existing patents? Cheers, Mark -- Dave: Just a question. What use is a unicyle with no seat? And no

Re: Versioning file system

2007-06-16 Thread Mark Williamson
I reviewed your sample implementation, and it appears to infringe 3 patents already.You should do some research on this. Are you able to tell us which areas of the code infringe existing patents? Cheers, Mark -- Dave: Just a question. What use is a unicyle with no seat? And no

Re: [Xen-devel] Re: [patch 20/20] XEN-paravirt: Add Xen virtual block device driver.

2007-01-15 Thread Mark Williamson
> > + > > + err = xenbus_printf(xbt, dev->nodename, > > + "ring-ref","%u", info->ring_ref); > > why do you need your own printf? xenbus_printf isn't a printf replacement - it is used for writing a formatted string into XenStore (which contains VM configuration data in a

Re: [Xen-devel] Re: [patch 20/20] XEN-paravirt: Add Xen virtual block device driver.

2007-01-15 Thread Mark Williamson
+ + err = xenbus_printf(xbt, dev-nodename, + ring-ref,%u, info-ring_ref); why do you need your own printf? xenbus_printf isn't a printf replacement - it is used for writing a formatted string into XenStore (which contains VM configuration data in a

Re: [Xen-devel] Re: [XEN] using shmfs for swapspace

2005-01-26 Thread Mark Williamson
> > - Pseudo faults: > > These are a problem, because they turn what would be a single > pageout into a pageout, a pagein, and another pageout, in > effect tripling the amount of IO that needs to be done. The Disco VMM tackled this by detecting attempts to double-page using a special virtual

Re: [Xen-devel] Re: [XEN] using shmfs for swapspace

2005-01-26 Thread Mark Williamson
- Pseudo faults: These are a problem, because they turn what would be a single pageout into a pageout, a pagein, and another pageout, in effect tripling the amount of IO that needs to be done. The Disco VMM tackled this by detecting attempts to double-page using a special virtual swap