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Goncalves" Subject: [PATCH v4 0/2] kexec, panic: Making crash_kexec() NMI safe Date: Thu, 30 Jun 2022 23:32:56 +0100 Message-Id: <20220630223258.4144112-1-vschneid@redhat.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=vschneid@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220630_153314_865225_A474FB0F X-CRM114-Status: UNSURE ( 9.33 ) X-CRM114-Notice: Please train this message. X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org Hi folks, Here's ~v3~ v4 where we now completely get rid of kexec_mutex. o Patch 1 makes sure all kexec_mutex acquisitions are trylocks. This prevents having to add any while(atomic_cmpxchg()) loops which I'd really hate to see here. If that can't be done then I think we're better off with the combined mutex+atomic var approach. o Patch 2 does the mutex -> atomic var switch. Revisions ========= v3 -> v4 ++++++++ o Someone forgot to Cc LKML on v3... v2 -> v3 ++++++++ o Dropped kexec_mutex entirely and made the atomic variable the one true lock for kexec (Eric) v1 -> v2 ++++++++ o Changed from Peterson-like synchronization to simpler atomic_cmpxchg (Petr) o Slightly reworded changelog o Added Fixes: tag. Technically should be up to since kexec can happen in an NMI, but that isn't such a clear target Cheers, Valentin Valentin Schneider (2): kexec: Turn all kexec_mutex acquisitions into trylocks panic, kexec: Make __crash_kexec() NMI safe include/linux/kexec.h | 2 +- kernel/kexec.c | 11 ++++------- kernel/kexec_core.c | 28 ++++++++++++++++------------ kernel/kexec_file.c | 4 ++-- kernel/kexec_internal.h | 15 ++++++++++++++- kernel/ksysfs.c | 7 ++++++- 6 files changed, 43 insertions(+), 24 deletions(-) -- 2.31.1 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec