All of lore.kernel.org
 help / color / mirror / Atom feed
From: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
To: Bart Van Assche <bvanassche@acm.org>,
	Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	Christophe Leroy <chleroy@kernel.org>,
	Shrikanth Hegde <sshegde@linux.ibm.com>, Qian Cai <cai@lca.pw>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH] powerpc/iommu: Fix an RCU read lock leak in mm_iommu_is_devmem()
Date: Tue, 27 Oct 2026 06:43:59 +0530	[thread overview]
Message-ID: <bj8g54iw.ritesh.list@gmail.com> (raw)
In-Reply-To: <56f0c45723ee53149a21ceb599010e957457afd8.1793044370.git.bvanassche@acm.org>

Bart Van Assche <bvanassche@acm.org> writes:

> mm_iommu_is_devmem() returns true from inside its RCU read-side
> critical section without calling rcu_read_unlock(). Neither caller,
> iommu_tce_xchg_no_kill() nor tce_page_is_contained(), drops the RCU
> read lock, so every successful lookup leaks one RCU read lock. Fix this
> by calling rcu_read_unlock() before returning true. The pointer to the
> list element is not used after the RCU read lock is dropped.
>
> Fixes: b5952f8125ae ("powerpc/mm/book3s64/iommu: fix some RCU-list locks")

Thanks Bart, but this was caught as part of Clang's context analysis
work on powerpc.  It is already posted here [1]. Could you review that
instead?

[1]: https://lore.kernel.org/linuxppc-dev/04e4dafde56fe4b055fbd763dc0e119862073c6d.1790590014.git.ritesh.list@gmail.com/

-ritesh


      parent reply	other threads:[~2026-10-27  4:07 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-26 19:52 [PATCH] powerpc/iommu: Fix an RCU read lock leak in mm_iommu_is_devmem() Bart Van Assche
2026-10-26 20:27 ` Markus Elfring
2026-10-26 20:33   ` Bart Van Assche
2026-10-27  1:13 ` Ritesh Harjani [this message]

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=bj8g54iw.ritesh.list@gmail.com \
    --to=ritesh.list@gmail.com \
    --cc=bvanassche@acm.org \
    --cc=cai@lca.pw \
    --cc=chleroy@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=maddy@linux.ibm.com \
    --cc=mpe@ellerman.id.au \
    --cc=npiggin@gmail.com \
    --cc=sshegde@linux.ibm.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.