From: Brian Ruley Date: Wed, 15 Apr 2026 17:12:48 +0000 (+0100) Subject: ARM: 9472/1: fix race condition on PG_dcache_clean in __sync_icache_dcache() X-Git-Tag: v7.1-rc1~8^2~1^3 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=75f9a484e817adea211c73f89ed938a2b2f90953;p=thirdparty%2Flinux.git ARM: 9472/1: fix race condition on PG_dcache_clean in __sync_icache_dcache() This bug was already discovered and fixed for arm64 in commit 588a513d3425 ("arm64: Fix race condition on PG_dcache_clean in __sync_icache_dcache()"). Verified with added instrumentation to track dcache flushes in a ring buffer, as shown by the (distilled) output: kernel: SIGILL at b6b80ac0 cpu 1 pid 32663 linux_pte=8eff659f hw_pte=8eff6e7e young=1 exec=1 kernel: dcache flush START cpu0 pfn=8eff6 ts=48629557020154 kernel: dcache flush SKIPPED cpu1 pfn=8eff6 ts=48629557020154 kernel: dcache flush FINISH cpu0 pfn=8eff6 ts=48629557036154 audisp-syslog: comm="journalctl" exe="/usr/bin/journalctl" sig=4 [...] Discussions in the mailing list mentioned that arch/arm is also affected but the fix was never applied to it [1][2]. Apply the change now, since the race condition can cause sporadic SIGILL's and SEGV's especially while under high memory pressure. Link: https://lore.kernel.org/all/adzMOdySgMIePcue@willie-the-truck [1] Link: https://lore.kernel.org/all/20210514095001.13236-1-catalin.marinas@arm.com [2] Signed-off-by: Brian Ruley Reviewed-by: Will Deacon Cc: Fixes: 6012191aa9c6 ("ARM: 6380/1: Introduce __sync_icache_dcache() for VIPT caches") Signed-off-by: Will Deacon Signed-off-by: Russell King (Oracle) --- diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c index 19470d938b236..4d7ef5cc36b66 100644 --- a/arch/arm/mm/flush.c +++ b/arch/arm/mm/flush.c @@ -304,8 +304,10 @@ void __sync_icache_dcache(pte_t pteval) else mapping = NULL; - if (!test_and_set_bit(PG_dcache_clean, &folio->flags.f)) + if (!test_bit(PG_dcache_clean, &folio->flags.f)) { __flush_dcache_folio(mapping, folio); + set_bit(PG_dcache_clean, &folio->flags.f); + } if (pte_exec(pteval)) __flush_icache_all();