From: Michal Hocko <mhocko@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: dsterba@suse.cz, Joe Perches <joe@perches.com>,
Waiman Long <longman@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Howells <dhowells@redhat.com>,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Dan Carpenter <dan.carpenter@oracle.com>,
"Jason A . Donenfeld" <Jason@zx2c4.com>,
linux-mm@kvack.org, keyrings@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
linux-pm@vger.kernel.org,
linux-stm32@st-md-mailman.stormreply.com,
linux-amlogic@lists.infradead.org,
linux-mediatek@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-ppp@vger.kernel.org,
wireguard@lists.zx2c4.com, linux-wireless@vger.kernel.org,
devel@driverdev.osuosl.org, linux-scsi@vger.kernel.org,
target-devel@vger.kernel.org, linux-btrfs@vger.kernel.org,
linux-cifs@vger.kernel.org, linux-fscrypt@vger.kernel.org,
ecryptfs@vger.kernel.org, kasan-dev@googlegroups.com,
linux-bluetooth@vger.kernel.org, linux-wpan@vger.kernel.org,
linux-sctp@vger.kernel.org, linux-nfs@vger.kernel.org,
tipc-discussion@lists.sourceforge.net,
linux-security-module@vger.kernel.org,
linux-integrity@vger.kernel.org
Subject: Re: [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree_sensitive()
Date: Wed, 17 Jun 2020 13:31:57 +0200 [thread overview]
Message-ID: <20200617113157.GM9499@dhcp22.suse.cz> (raw)
In-Reply-To: <20200617110820.GG8681@bombadil.infradead.org>
On Wed 17-06-20 04:08:20, Matthew Wilcox wrote:
> On Wed, Jun 17, 2020 at 09:12:12AM +0200, Michal Hocko wrote:
> > On Tue 16-06-20 17:37:11, Matthew Wilcox wrote:
> > > Not just performance critical, but correctness critical. Since kvfree()
> > > may allocate from the vmalloc allocator, I really think that kvfree()
> > > should assert that it's !in_atomic(). Otherwise we can get into trouble
> > > if we end up calling vfree() and have to take the mutex.
> >
> > FWIW __vfree already checks for atomic context and put the work into a
> > deferred context. So this should be safe. It should be used as a last
> > resort, though.
>
> Actually, it only checks for in_interrupt().
You are right. I have misremembered. You have made me look (thanks) ...
> If you call vfree() under
> a spinlock, you're in trouble. in_atomic() only knows if we hold a
> spinlock for CONFIG_PREEMPT, so it's not safe to check for in_atomic()
> in __vfree(). So we need the warning in order that preempt people can
> tell those without that there is a bug here.
... Unless I am missing something in_interrupt depends on preempt_count() as
well so neither of the two is reliable without PREEMPT_COUNT configured.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-06-17 11:32 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 1:57 [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree_sensitive() Waiman Long
2020-06-16 1:57 ` [PATCH v4 1/3] mm/slab: Use memzero_explicit() in kzfree() Waiman Long
2020-06-16 3:30 ` Eric Biggers
2020-06-16 13:05 ` Waiman Long
2020-06-16 15:46 ` David Howells
2020-06-16 6:42 ` Michal Hocko
2020-06-16 9:08 ` Dan Carpenter
2020-06-16 1:57 ` [PATCH v4 2/3] mm, treewide: Rename kzfree() to kfree_sensitive() Waiman Long
2020-06-16 14:26 ` Dan Carpenter
2020-06-16 15:05 ` Waiman Long
2020-06-16 1:57 ` [PATCH v4 3/3] btrfs: Use kfree() in btrfs_ioctl_get_subvol_info() Waiman Long
2020-06-16 14:48 ` David Sterba
2020-06-16 15:05 ` Waiman Long
2020-06-16 18:53 ` [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree_sensitive() Joe Perches
2020-06-16 19:43 ` Waiman Long
2020-06-16 19:46 ` Jason A. Donenfeld
2020-06-16 20:01 ` Waiman Long
2020-06-16 21:14 ` Matthew Wilcox
2020-06-16 23:01 ` David Sterba
2020-06-17 0:37 ` Matthew Wilcox
2020-06-17 7:12 ` Michal Hocko
2020-06-17 11:08 ` Matthew Wilcox
2020-06-17 11:31 ` Michal Hocko [this message]
2020-06-17 12:23 ` Matthew Wilcox
2020-06-17 12:55 ` Michal Hocko
2020-06-17 8:03 ` Jo -l
2020-06-17 21:31 ` Denis Efremov
2020-06-17 23:12 ` Joe Perches
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=20200617113157.GM9499@dhcp22.suse.cz \
--to=mhocko@kernel.org \
--cc=Jason@zx2c4.com \
--cc=akpm@linux-foundation.org \
--cc=dan.carpenter@oracle.com \
--cc=devel@driverdev.osuosl.org \
--cc=dhowells@redhat.com \
--cc=dsterba@suse.cz \
--cc=ecryptfs@vger.kernel.org \
--cc=hannes@cmpxchg.org \
--cc=jarkko.sakkinen@linux.intel.com \
--cc=jmorris@namei.org \
--cc=joe@perches.com \
--cc=kasan-dev@googlegroups.com \
--cc=keyrings@vger.kernel.org \
--cc=linux-amlogic@lists.infradead.org \
--cc=linux-bluetooth@vger.kernel.org \
--cc=linux-btrfs@vger.kernel.org \
--cc=linux-cifs@vger.kernel.org \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-fscrypt@vger.kernel.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mediatek@lists.infradead.org \
--cc=linux-mm@kvack.org \
--cc=linux-nfs@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=linux-ppp@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=linux-sctp@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=linux-stm32@st-md-mailman.stormreply.com \
--cc=linux-wireless@vger.kernel.org \
--cc=linux-wpan@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=longman@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=rientjes@google.com \
--cc=serge@hallyn.com \
--cc=target-devel@vger.kernel.org \
--cc=tipc-discussion@lists.sourceforge.net \
--cc=torvalds@linux-foundation.org \
--cc=virtualization@lists.linux-foundation.org \
--cc=willy@infradead.org \
--cc=wireguard@lists.zx2c4.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 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).