From: Mark Rutland <mark.rutland@arm.com>
To: linux-kernel@vger.kernel.org
Cc: ak@linux.intel.com, akpm@linux-foundation.org,
bigeasy@linutronix.de, bp@suse.de, catalin.marinas@arm.com,
davem@davemloft.net, hch@lst.de, kan.liang@intel.com,
mark.rutland@arm.com, mingo@kernel.org, peterz@infradead.org,
riel@surriel.com, will@kernel.org
Subject: [PATCH 8/9] x86/fpu: correctly check for kthreads
Date: Wed, 14 Aug 2019 11:41:30 +0100 [thread overview]
Message-ID: <20190814104131.20190-9-mark.rutland@arm.com> (raw)
In-Reply-To: <20190814104131.20190-1-mark.rutland@arm.com>
Per commit:
0cecca9d03c964ab ("x86/fpu: Eager switch PKRU state")
... switch_fpu_state() is trying to distinguish user threads from
kthreads, such that kthreads consistently use init_pkru_value. It does
do by looking at current->mm.
In general, a non-NULL current->mm doesn't imply that current is a
kthread, as kthreads can install an mm via use_mm(), and so it's
preferable to use is_kthread() to determine whether a thread is a
kthread.
For consistency, let's use is_kthread() here.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/include/asm/fpu/internal.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 4c95c365058a..ed3d85fa7c67 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -607,7 +607,7 @@ static inline void switch_fpu_finish(struct fpu *new_fpu)
* PKRU state is switched eagerly because it needs to be valid before we
* return to userland e.g. for a copy_to_user() operation.
*/
- if (current->mm) {
+ if (!is_kthread(current)) {
pk = get_xsave_addr(&new_fpu->state.xsave, XFEATURE_PKRU);
if (pk)
pkru_val = pk->pkru;
--
2.11.0
next prev parent reply other threads:[~2019-08-14 10:42 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-14 10:41 [PATCH 0/9] kthread detection cleanup Mark Rutland
2019-08-14 10:41 ` [PATCH 1/9] sched/core: add is_kthread() helper Mark Rutland
2019-08-14 11:26 ` Geert Uytterhoeven
2019-08-14 11:32 ` Mark Rutland
2019-08-19 8:52 ` Ingo Molnar
2019-08-21 11:21 ` Peter Zijlstra
2019-08-14 10:41 ` [PATCH 2/9] sched: treewide: use is_kthread() Mark Rutland
2019-08-14 11:27 ` Geert Uytterhoeven
2019-08-14 12:39 ` Sebastian Andrzej Siewior
2019-08-14 13:35 ` Mark Rutland
2019-08-14 13:37 ` Valentin Schneider
2019-08-14 10:41 ` [PATCH 3/9] kmemleak: correctly check for kthreads Mark Rutland
2019-08-14 16:39 ` Catalin Marinas
2019-08-14 10:41 ` [PATCH 4/9] arm/perf: " Mark Rutland
2019-08-14 10:41 ` [PATCH 5/9] arm64: correctly check for ktrheads Mark Rutland
2019-08-14 16:40 ` Catalin Marinas
2019-08-14 10:41 ` [PATCH 6/9] sparc/perf: correctly check for kthreads Mark Rutland
2019-08-14 16:26 ` David Miller
2019-08-14 10:41 ` [PATCH 7/9] x86/lbr: " Mark Rutland
2019-08-14 10:41 ` Mark Rutland [this message]
2019-08-14 13:07 ` [PATCH 8/9] x86/fpu: " Sebastian Andrzej Siewior
2019-08-14 13:39 ` Mark Rutland
2019-08-14 14:55 ` Sebastian Andrzej Siewior
2019-08-14 10:41 ` [PATCH 9/9] samples/kretprobe: " Mark Rutland
2019-08-14 13:43 ` [PATCH 0/9] kthread detection cleanup Valentin Schneider
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=20190814104131.20190-9-mark.rutland@arm.com \
--to=mark.rutland@arm.com \
--cc=ak@linux.intel.com \
--cc=akpm@linux-foundation.org \
--cc=bigeasy@linutronix.de \
--cc=bp@suse.de \
--cc=catalin.marinas@arm.com \
--cc=davem@davemloft.net \
--cc=hch@lst.de \
--cc=kan.liang@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=riel@surriel.com \
--cc=will@kernel.org \
/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).