On Mon, Feb 18, 2013 at 01:44:35PM +0100, Svatopluk Kraus wrote: > Hi, > > the access to sysmaps_pcpu[] should be atomic with respect to > thread migration. Otherwise, a sysmaps for one CPU can be stolen by > another CPU and the purpose of per CPU sysmaps is broken. A patch is > enclosed. And, what are the problem caused by the 'otherwise' ? I do not see any. Really, taking the mutex while bind to a CPU could be deadlock-prone under some situations. This was discussed at least one more time. Might be, a comment saying that there is no issue should be added. > > Svata > > Index: sys/i386/i386/pmap.c > =================================================================== > --- sys/i386/i386/pmap.c (revision 246831) > +++ sys/i386/i386/pmap.c (working copy) > _at__at_ -4146,11 +4146,11 _at__at_ > { > struct sysmaps *sysmaps; > > + sched_pin(); > sysmaps = &sysmaps_pcpu[PCPU_GET(cpuid)]; > mtx_lock(&sysmaps->lock); > if (*sysmaps->CMAP2) > panic("pmap_zero_page: CMAP2 busy"); > - sched_pin(); > *sysmaps->CMAP2 = PG_V | PG_RW | VM_PAGE_TO_PHYS(m) | PG_A | PG_M | > pmap_cache_bits(m->md.pat_mode, 0); > invlcaddr(sysmaps->CADDR2); > _at__at_ -4171,11 +4171,11 _at__at_ > { > struct sysmaps *sysmaps; > > + sched_pin(); > sysmaps = &sysmaps_pcpu[PCPU_GET(cpuid)]; > mtx_lock(&sysmaps->lock); > if (*sysmaps->CMAP2) > panic("pmap_zero_page_area: CMAP2 busy"); > - sched_pin(); > *sysmaps->CMAP2 = PG_V | PG_RW | VM_PAGE_TO_PHYS(m) | PG_A | PG_M | > pmap_cache_bits(m->md.pat_mode, 0); > invlcaddr(sysmaps->CADDR2); > _at__at_ -4220,13 +4220,13 _at__at_ > { > struct sysmaps *sysmaps; > > + sched_pin(); > sysmaps = &sysmaps_pcpu[PCPU_GET(cpuid)]; > mtx_lock(&sysmaps->lock); > if (*sysmaps->CMAP1) > panic("pmap_copy_page: CMAP1 busy"); > if (*sysmaps->CMAP2) > panic("pmap_copy_page: CMAP2 busy"); > - sched_pin(); > invlpg((u_int)sysmaps->CADDR1); > invlpg((u_int)sysmaps->CADDR2); > *sysmaps->CMAP1 = PG_V | VM_PAGE_TO_PHYS(src) | PG_A | > _at__at_ -5072,11 +5072,11 _at__at_ > vm_offset_t sva, eva; > > if ((cpu_feature & CPUID_CLFSH) != 0) { > + sched_pin(); > sysmaps = &sysmaps_pcpu[PCPU_GET(cpuid)]; > mtx_lock(&sysmaps->lock); > if (*sysmaps->CMAP2) > panic("pmap_flush_page: CMAP2 busy"); > - sched_pin(); > *sysmaps->CMAP2 = PG_V | PG_RW | VM_PAGE_TO_PHYS(m) | > PG_A | PG_M | pmap_cache_bits(m->md.pat_mode, 0); > invlcaddr(sysmaps->CADDR2); > _______________________________________________ > freebsd-current_at_freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org"
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