From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Oleg Nesterov <oleg@redhat.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 01/12] uprobes: split THPs before trying replace them
Date: Wed, 25 Jan 2017 08:55:22 -0800 [thread overview]
Message-ID: <20170125165522.GA11569@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170124222217.GB19920@node.shutemov.name>
> >
> > > For THPs page_check_address() always fails. It's better to split them
> > > first before trying to replace.
> >
> > So what does this mean. uprobes simply fails to work when trying to
> > place a probe into a THP memory region?
>
> Looks like we can end up with endless retry loop in uprobe_write_opcode().
>
> > How come nobody noticed (and reported) this when using the feature?
>
> I guess it's not often used for anon memory.
>
The first time the breakpoint is hit on a page, it replaces the text
page with anon page. Now lets assume we insert breakpoints in all the
pages in a range. Here each page is individually replaced by a non THP
anonpage. (since we dont have bulk breakpoint insertion support,
breakpoint insertion happens one at a time). Now the only interesting
case may be when each of these replaced pages happen to be physically
contiguous so that THP kicks in to replace all of these pages with one
THP page. Can happen in practice?
Are there any other cases that I have missed?
--
Thanks and Regards
Srikar Dronamraju
WARNING: multiple messages have this Message-ID (diff)
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Oleg Nesterov <oleg@redhat.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 01/12] uprobes: split THPs before trying replace them
Date: Wed, 25 Jan 2017 08:55:22 -0800 [thread overview]
Message-ID: <20170125165522.GA11569@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170124222217.GB19920@node.shutemov.name>
> >
> > > For THPs page_check_address() always fails. It's better to split them
> > > first before trying to replace.
> >
> > So what does this mean. uprobes simply fails to work when trying to
> > place a probe into a THP memory region?
>
> Looks like we can end up with endless retry loop in uprobe_write_opcode().
>
> > How come nobody noticed (and reported) this when using the feature?
>
> I guess it's not often used for anon memory.
>
The first time the breakpoint is hit on a page, it replaces the text
page with anon page. Now lets assume we insert breakpoints in all the
pages in a range. Here each page is individually replaced by a non THP
anonpage. (since we dont have bulk breakpoint insertion support,
breakpoint insertion happens one at a time). Now the only interesting
case may be when each of these replaced pages happen to be physically
contiguous so that THP kicks in to replace all of these pages with one
THP page. Can happen in practice?
Are there any other cases that I have missed?
--
Thanks and Regards
Srikar Dronamraju
--
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>
next prev parent reply other threads:[~2017-01-25 16:56 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-24 16:28 [PATCH 00/12] Fix few rmap-related THP bugs Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-24 16:28 ` [PATCH 01/12] uprobes: split THPs before trying replace them Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-24 18:08 ` Rik van Riel
2017-01-24 18:08 ` Rik van Riel
2017-01-24 21:28 ` Andrew Morton
2017-01-24 21:28 ` Andrew Morton
2017-01-24 22:22 ` Kirill A. Shutemov
2017-01-24 22:22 ` Kirill A. Shutemov
2017-01-24 22:35 ` Andrew Morton
2017-01-24 22:35 ` Andrew Morton
2017-01-24 22:56 ` Kirill A. Shutemov
2017-01-24 22:56 ` Kirill A. Shutemov
2017-01-25 16:55 ` Srikar Dronamraju [this message]
2017-01-25 16:55 ` Srikar Dronamraju
2017-01-25 17:44 ` Rik van Riel
2017-01-25 17:44 ` Kirill A. Shutemov
2017-01-25 17:44 ` Kirill A. Shutemov
2017-01-25 18:35 ` Johannes Weiner
2017-01-25 18:35 ` Johannes Weiner
2017-01-25 18:38 ` Kirill A. Shutemov
2017-01-25 18:38 ` Kirill A. Shutemov
2017-01-26 2:54 ` Srikar Dronamraju
2017-01-26 2:54 ` Srikar Dronamraju
2017-01-25 18:22 ` Johannes Weiner
2017-01-25 18:22 ` Johannes Weiner
2017-01-24 16:28 ` [PATCH 02/12] mm: introduce page_check_walk() Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-24 21:41 ` Andrew Morton
2017-01-24 21:41 ` Andrew Morton
2017-01-24 22:50 ` Kirill A. Shutemov
2017-01-24 22:50 ` Kirill A. Shutemov
2017-01-24 22:55 ` Andrew Morton
2017-01-24 22:55 ` Andrew Morton
2017-01-25 17:53 ` Kirill A. Shutemov
2017-01-25 17:53 ` Kirill A. Shutemov
2017-01-25 1:19 ` kbuild test robot
2017-01-25 1:19 ` kbuild test robot
2017-01-25 1:59 ` kbuild test robot
2017-01-25 1:59 ` kbuild test robot
2017-01-24 16:28 ` [PATCH 03/12] mm: fix handling PTE-mapped THPs in page_referenced() Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-24 16:28 ` [PATCH 04/12] mm: fix handling PTE-mapped THPs in page_idle_clear_pte_refs() Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-24 16:28 ` [PATCH 05/12] mm, rmap: check all VMAs that PTE-mapped THP can be part of Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-24 16:28 ` [PATCH 06/12] mm: convert page_mkclean_one() to page_check_walk() Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-25 1:44 ` kbuild test robot
2017-01-25 1:44 ` kbuild test robot
2017-01-25 2:00 ` kbuild test robot
2017-01-25 2:00 ` kbuild test robot
2017-01-24 16:28 ` [PATCH 07/12] mm: convert try_to_unmap_one() " Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-25 3:13 ` kbuild test robot
2017-01-25 3:13 ` kbuild test robot
2017-01-24 16:28 ` [PATCH 08/12] mm, ksm: convert write_protect_page() " Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-24 16:28 ` [PATCH 09/12] mm, uprobes: convert __replace_page() " Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-26 2:58 ` Srikar Dronamraju
2017-01-26 2:58 ` Srikar Dronamraju
2017-01-24 16:28 ` [PATCH 10/12] mm: convert page_mapped_in_vma() " Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-24 16:28 ` [PATCH 11/12] mm: drop page_check_address{,_transhuge} Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-24 16:28 ` [PATCH 12/12] mm: convert remove_migration_pte() to page_check_walk() Kirill A. Shutemov
2017-01-24 16:28 ` Kirill A. Shutemov
2017-01-25 1:54 ` kbuild test robot
2017-01-25 1:54 ` kbuild test robot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170125165522.GA11569@linux.vnet.ibm.com \
--to=srikar@linux.vnet.ibm.com \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=hughd@google.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=kirill@shutemov.name \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=oleg@redhat.com \
--cc=peterz@infradead.org \
--cc=riel@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.