Date: Thu, 30 Apr 2020 18:30:33 -0700 From: Mark Millard <marklmi@yahoo.com> To: FreeBSD PowerPC ML <freebsd-ppc@freebsd.org>, FreeBSD Hackers <freebsd-hackers@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org> Subject: 32-bit powerpc head -r360311: lock order reversal between: "PROC (UMA zone)" and "kernelpmap (kernelpmap)": Is this expected? Message-ID: <013FB43E-7DB1-4A66-A6ED-12A891539788@yahoo.com> References: <013FB43E-7DB1-4A66-A6ED-12A891539788.ref@yahoo.com>
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Using artifact.ci's head -r360311 debug-kernel materials: = https://artifact.ci.freebsd.org/snapshot/head/r360311/powerpc/powerpc/kern= el*.txz I got the following notice: lock order reversal: 1st 0x1cbb680 PROC (UMA zone) @ /usr/src/sys/vm/uma_core.c:4387 2nd 0x113c99c kernelpmap (kernelpmap) @ = /usr/src/sys/powerpc/aim/mmu_oea.c:1524 stack backtrace: #0 0x5d1e5c at witness_debugger+0x94 #1 0x5d1b34 at witness_checkorder+0xb50 #2 0x51d774 at __mtx_lock_flags+0xcc #3 0x90902c at moea_kextract+0x5c #4 0x9462ac at pmap_kextract+0x98 #5 0x8a417c at zone_release+0xf0 #6 0x8abc14 at bucket_drain+0x2f0 #7 0x8ab64c at bucket_free+0x54 #8 0x8ab8bc at bucket_cache_reclaim+0x1bc #9 0x8ab3c4 at zone_reclaim+0x128 #10 0x8a7e60 at uma_reclaim+0x1d0 #11 0x8d96ac at vm_pageout_worker+0x4d8 #12 0x8d91c0 at vm_pageout+0x1b0 #13 0x4f67a0 at fork_exit+0xb0 #14 0x94892c at fork_trampoline+0xc Is the above interesting or is it one of the known-safe lock order reversals that should be ignored? (The notice is from something like 4.5 hours before I noticed it.) =3D=3D=3D Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)
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