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charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAPjlu2YC/x2MQQqAIBAAvxJ7TlitIPpKRIittYcsNCIS/97Sc WBmMiSKTAmGKkOkmxMfQUDXFbjNhpUUL8Jg0LTYa6M8P7On4Ijn47x459de0qjG99o6g9hhB1K fkUT9z+NUygdPKwdEaQAAAA== To: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Atish Patra , Samuel Holland , Andrea Parri Cc: Palmer Dabbelt , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Charlie Jenkins X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1071; i=charlie@rivosinc.com; h=from:subject:message-id; bh=XeL6GWit/pqjHiJc/lAmWKHdjpGQ7Hay1LB5z79tDoE=; b=owGbwMvMwCHWx5hUnlvL8Y3xtFoSQ9rup7+jX5jK+HTHn2h1NFjOsFy6TvLxppccbIU/Xh0JX HowMPdDRykLgxgHg6yYIgvPtQbm1jv6ZUdFyybAzGFlAhnCwMUpABPpV2Nk2D51+xbPPfvqiizf mM2972bc/v9e9H6rOu/SXXccH250s2P4p6nypyLuR3PSrhV/Oi/OmeaiF/dAZtbMnBaTktWs727 d4gIA X-Developer-Key: i=charlie@rivosinc.com; a=openpgp; fpr=7D834FF11B1D8387E61C776FFB10D1F27D6B1354 There are two race conditions possible with PR_RISCV_SET_ICACHE_FLUSH_CTX. The first one can be seen by enabling DEBUG_PREEMPT and using this prctl which will warn with BUG: using smp_processor_id() in preemptible. This can be fixed by disabling preemption during this prctl handling. Another race condition is present when the mm->context.icache_stale_mask is changed by a thread while a different thread in the same mm context is between switch_mm() and switch_to() during a context switch. Signed-off-by: Charlie Jenkins --- Charlie Jenkins (2): riscv: Disable preemption while handling PR_RISCV_CTX_SW_FENCEI_OFF riscv: Eagerly flush in flush_icache_deferred() arch/riscv/include/asm/switch_to.h | 19 ++++++++++++++++--- arch/riscv/mm/cacheflush.c | 13 +++++++------ arch/riscv/mm/context.c | 6 +----- 3 files changed, 24 insertions(+), 14 deletions(-) --- base-commit: 7c626ce4bae1ac14f60076d00eafe71af30450ba change-id: 20240812-fix_fencei_optimization-3f81ac200505 -- - Charlie