linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Pasha Tatashin <pasha.tatashin@soleen.com>
To: pasha.tatashin@soleen.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-m68k@lists.linux-m68k.org,
	anshuman.khandual@arm.com, willy@infradead.org,
	akpm@linux-foundation.org, william.kucharski@oracle.com,
	mike.kravetz@oracle.com, vbabka@suse.cz, geert@linux-m68k.org,
	schmitzmic@gmail.com, rostedt@goodmis.org, mingo@redhat.com,
	hannes@cmpxchg.org, guro@fb.com, songmuchun@bytedance.com,
	weixugc@google.com, gthelen@google.com, rientjes@google.com,
	pjt@google.com
Subject: [RFC v2 00/10] Hardening page _refcount
Date: Wed, 17 Nov 2021 01:20:49 +0000	[thread overview]
Message-ID: <20211117012059.141450-1-pasha.tatashin@soleen.com> (raw)

From: Pasha Tatashin <tatashin@google.com>

Changelog:
- use the "fetch" variant instead of "return" of atomic instructions
- allow negative values, as we are using all 32-bits of _refcount.


It is hard to root cause _refcount problems, because they usually
manifest after the damage has occurred.  Yet, they can lead to
catastrophic failures such memory corruptions. There were a number
of refcount related issues discovered recently [1], [2], [3].

Improve debugability by adding more checks that ensure that
page->_refcount never turns negative (i.e. double free does not
happen, or free after freeze etc).

- Check for overflow and underflow right from the functions that
  modify _refcount
- Remove set_page_count(), so we do not unconditionally overwrite
  _refcount with an unrestrained value
- Trace return values in all functions that modify _refcount

Applies against next-20211116.

Previous verions:
RFCv1: https://lore.kernel.org/all/20211026173822.502506-1-pasha.tatashin@soleen.com

[1] https://lore.kernel.org/all/xr9335nxwc5y.fsf@gthelen2.svl.corp.google.com
[2] https://lore.kernel.org/all/1582661774-30925-2-git-send-email-akaher@vmware.com
[3] https://lore.kernel.org/all/20210622021423.154662-3-mike.kravetz@oracle.com

Pasha Tatashin (10):
  mm: page_ref_add_unless() does not trace 'u' argument
  mm: add overflow and underflow checks for page->_refcount
  mm: Avoid using set_page_count() in set_page_recounted()
  mm: remove set_page_count() from page_frag_alloc_align
  mm: avoid using set_page_count() when pages are freed into allocator
  mm: rename init_page_count() -> page_ref_init()
  mm: remove set_page_count()
  mm: simplify page_ref_* functions
  mm: do not use atomic_set_release in page_ref_unfreeze()
  mm: use atomic_cmpxchg_acquire in page_ref_freeze().

 arch/m68k/mm/motorola.c         |   2 +-
 include/linux/mm.h              |   2 +-
 include/linux/page_ref.h        | 159 +++++++++++++++-----------------
 include/trace/events/page_ref.h |  99 +++++++++++++++-----
 mm/debug_page_ref.c             |  30 ++----
 mm/internal.h                   |   6 +-
 mm/page_alloc.c                 |  19 ++--
 7 files changed, 180 insertions(+), 137 deletions(-)

-- 
2.34.0.rc1.387.gb447b232ab-goog


             reply	other threads:[~2021-11-17  1:21 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-17  1:20 Pasha Tatashin [this message]
2021-11-17  1:20 ` [RFC v2 01/10] mm: page_ref_add_unless() does not trace 'u' argument Pasha Tatashin
2021-11-17  1:20 ` [RFC v2 02/10] mm: add overflow and underflow checks for page->_refcount Pasha Tatashin
2021-11-17  1:20 ` [RFC v2 03/10] mm: Avoid using set_page_count() in set_page_recounted() Pasha Tatashin
2021-11-17  1:20 ` [RFC v2 04/10] mm: remove set_page_count() from page_frag_alloc_align Pasha Tatashin
2021-11-17  1:20 ` [RFC v2 05/10] mm: avoid using set_page_count() when pages are freed into allocator Pasha Tatashin
2021-11-17  1:20 ` [RFC v2 06/10] mm: rename init_page_count() -> page_ref_init() Pasha Tatashin
2021-11-17  1:20 ` [RFC v2 07/10] mm: remove set_page_count() Pasha Tatashin
2021-11-17  1:20 ` [RFC v2 08/10] mm: simplify page_ref_* functions Pasha Tatashin
2021-11-17  1:20 ` [RFC v2 09/10] mm: do not use atomic_set_release in page_ref_unfreeze() Pasha Tatashin
2021-11-17  1:20 ` [RFC v2 10/10] mm: use atomic_cmpxchg_acquire in page_ref_freeze() Pasha Tatashin

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=20211117012059.141450-1-pasha.tatashin@soleen.com \
    --to=pasha.tatashin@soleen.com \
    --cc=akpm@linux-foundation.org \
    --cc=anshuman.khandual@arm.com \
    --cc=geert@linux-m68k.org \
    --cc=gthelen@google.com \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-m68k@lists.linux-m68k.org \
    --cc=linux-mm@kvack.org \
    --cc=mike.kravetz@oracle.com \
    --cc=mingo@redhat.com \
    --cc=pjt@google.com \
    --cc=rientjes@google.com \
    --cc=rostedt@goodmis.org \
    --cc=schmitzmic@gmail.com \
    --cc=songmuchun@bytedance.com \
    --cc=vbabka@suse.cz \
    --cc=weixugc@google.com \
    --cc=william.kucharski@oracle.com \
    --cc=willy@infradead.org \
    --subject='Re: [RFC v2 00/10] Hardening page _refcount' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).