Re: svn commit: r360233 - in head: contrib/jemalloc . . . : This partially breaks a 2-socket 32-bit powerpc (old PowerMac G4) based on head -r360311

On 2020-Jun-11, at 16:49, Mark Millard <marklmi at yahoo.com> wrote:

> On 2020-Jun-11, at 14:42, Justin Hibbits <chmeeedalf at gmail.com> wrote:
> 
> On Thu, 11 Jun 2020 14:36:37 -0700
> Mark Millard <[email protected]> wrote:
> 
>> On 2020-Jun-11, at 13:55, Justin Hibbits <chmeeedalf at gmail.com>
>> wrote:
>> 
>>> On Wed, 10 Jun 2020 18:56:57 -0700
>>> Mark Millard <[email protected]> wrote:
> . . .
>> 
>> 
>>> That said, the attached patch effectively copies
>>> what's done in OEA6464 into OEA pmap.  Can you test it?  
>> 
>> I'll try it once I get a chance, probably later
>> today.
>> . . .
> 
> No luck at the change being a fix, I'm afraid.
> 
> I verified that the build ended up with
> 
> 00926cb0 <moea_protect+0x2ec> bl      008e8dc8 <PHYS_TO_VM_PAGE>
> 00926cb4 <moea_protect+0x2f0> mr      r27,r3
> 00926cb8 <moea_protect+0x2f4> addi    r3,r3,36
> 00926cbc <moea_protect+0x2f8> hwsync
> 00926cc0 <moea_protect+0x2fc> lwarx   r25,0,r3
> 00926cc4 <moea_protect+0x300> li      r4,0
> 00926cc8 <moea_protect+0x304> stwcx.  r4,0,r3
> 00926ccc <moea_protect+0x308> bne-    00926cc0 <moea_protect+0x2fc>
> 00926cd0 <moea_protect+0x30c> andi.   r3,r25,128
> 00926cd4 <moea_protect+0x310> beq     00926ce0 <moea_protect+0x31c>
> 00926cd8 <moea_protect+0x314> mr      r3,r27
> 00926cdc <moea_protect+0x318> bl      008e9874 <vm_page_dirty_KBI>
> 
> in the installed kernel. So I doubt a
> mis-build would be involved. It is a
> head -r360311 based context still. World is
> without MALLOC_PRODUCTION so that jemalloc
> code executes its asserts, catching more
> and earlier than otherwise.
> 
> First test . . .
> 
> The only thing that the witness kernel reported was:
> 
> Jun 11 15:58:16 FBSDG4S2 kernel: lock order reversal:
> Jun 11 15:58:16 FBSDG4S2 kernel:  1st 0x216fb00 Mountpoints (UMA zone) @ /usr/src/sys/vm/uma_core.c:4387
> Jun 11 15:58:16 FBSDG4S2 kernel:  2nd 0x1192d2c kernelpmap (kernelpmap) @ /usr/src/sys/powerpc/aim/mmu_oea.c:1524
> Jun 11 15:58:16 FBSDG4S2 kernel: stack backtrace:
> Jun 11 15:58:16 FBSDG4S2 kernel: #0 0x5ec164 at witness_debugger+0x94
> Jun 11 15:58:16 FBSDG4S2 kernel: #1 0x5ebe3c at witness_checkorder+0xb50
> Jun 11 15:58:16 FBSDG4S2 kernel: #2 0x536d5c at __mtx_lock_flags+0xcc
> Jun 11 15:58:16 FBSDG4S2 kernel: #3 0x92636c at moea_kextract+0x5c
> Jun 11 15:58:16 FBSDG4S2 kernel: #4 0x965d30 at pmap_kextract+0x98
> Jun 11 15:58:16 FBSDG4S2 kernel: #5 0x8bfdbc at zone_release+0xf0
> Jun 11 15:58:16 FBSDG4S2 kernel: #6 0x8c7854 at bucket_drain+0x2f0
> Jun 11 15:58:16 FBSDG4S2 kernel: #7 0x8c728c at bucket_free+0x54
> Jun 11 15:58:16 FBSDG4S2 kernel: #8 0x8c74fc at bucket_cache_reclaim+0x1bc
> Jun 11 15:58:16 FBSDG4S2 kernel: #9 0x8c7004 at zone_reclaim+0x128
> Jun 11 15:58:16 FBSDG4S2 kernel: #10 0x8c3a40 at uma_reclaim+0x170
> Jun 11 15:58:16 FBSDG4S2 kernel: #11 0x8c3f70 at uma_reclaim_worker+0x68
> Jun 11 15:58:16 FBSDG4S2 kernel: #12 0x50fbac at fork_exit+0xb0
> Jun 11 15:58:16 FBSDG4S2 kernel: #13 0x9684ac at fork_trampoline+0xc
> 
> The processes that were hit were listed as:
> 
> Jun 11 15:59:11 FBSDG4S2 kernel: pid 971 (cron), jid 0, uid 0: exited on signal 11 (core dumped)
> Jun 11 16:02:59 FBSDG4S2 kernel: pid 1111 (stress), jid 0, uid 0: exited on signal 6 (core dumped)
> Jun 11 16:03:27 FBSDG4S2 kernel: pid 871 (mountd), jid 0, uid 0: exited on signal 6 (core dumped)
> Jun 11 16:03:40 FBSDG4S2 kernel: pid 1065 (su), jid 0, uid 0: exited on signal 6
> Jun 11 16:04:13 FBSDG4S2 kernel: pid 1088 (su), jid 0, uid 0: exited on signal 6
> Jun 11 16:04:28 FBSDG4S2 kernel: pid 968 (sshd), jid 0, uid 0: exited on signal 6
> 
> Jun 11 16:05:42 FBSDG4S2 kernel: pid 1028 (login), jid 0, uid 0: exited on signal 6
> 
> Jun 11 16:05:46 FBSDG4S2 kernel: pid 873 (nfsd), jid 0, uid 0: exited on signal 6 (core dumped)
> 
> 
> Rebooting and rerunning and showing the stress output and such
> (I did not capture copies during the first test, but the first
> test had similar messages at the same sort of points):
> 
> Second test . . .
> 
> # stress -m 2 --vm-bytes 1700M
> stress: info: [1166] dispatching hogs: 0 cpu, 0 io, 2 vm, 0 hdd
> <jemalloc>: /usr/src/contrib/jemalloc/include/jemalloc/internal/arena_inlines_b.h:258: Failed assertion: "slab == extent_slab_get(extent)"
> <jemalloc>: /usr/src/contrib/jemalloc/include/jemalloc/internal/arena_inlines_b.h:258: Failed assertion: "slab == extent_slab_get(extent)"
> ^C
> 
> # exit
> <jemalloc>: /usr/src/contrib/jemalloc/include/jemalloc/internal/sz.h:200: Failed assertion: "ret == sz_index2size_compute(index)"
> Abort trap
> 
> The other stuff was similar to to first test, not repeated here.

The updated code looks odd to me for how "m" is
handled (part of a egrep to ensure I show all the
usage of m):

moea_protect(mmu_t mmu, pmap_t pm, vm_offset_t sva, vm_offset_t eva,
        vm_page_t       m;
                        if (pm != kernel_pmap && m != NULL &&
                            (m->a.flags & PGA_EXECUTABLE) == 0 &&
                                if ((m->oflags & VPO_UNMANAGED) == 0)
                                        vm_page_aflag_set(m, PGA_EXECUTABLE);
                                m = PHYS_TO_VM_PAGE(old_pte.pte_lo & PTE_RPGN);
                                refchg = atomic_readandclear_32(&m->md.mdpg_attrs);
                                        vm_page_dirty(m);
                                        vm_page_aflag_set(m, PGA_REFERENCED);

Or more completely, with notes mixed in:

void 
moea_protect(mmu_t mmu, pmap_t pm, vm_offset_t sva, vm_offset_t eva,
    vm_prot_t prot)
{
        . . .
        vm_page_t       m;
        . . .
        for (pvo = RB_NFIND(pvo_tree, &pm->pmap_pvo, &key);
            pvo != NULL && PVO_VADDR(pvo) < eva; pvo = tpvo) {
                . . .
                if (pt != NULL) {
                        . . .
                        if (pm != kernel_pmap && m != NULL &&

NOTE: m seems to be uninitialized but tested for being NULL
above.

                            (m->a.flags & PGA_EXECUTABLE) == 0 &&

Note: This looks to potentially be using a random, non-NULL
value for m during evaluation of m->a.flags .

                        . . .

                        if ((pvo->pvo_vaddr & PVO_MANAGED) &&
                            (pvo->pvo_pte.prot & VM_PROT_WRITE)) {
                                m = PHYS_TO_VM_PAGE(old_pte.pte_lo & PTE_RPGN);

Note: m finally is potentially initialized(/set).

                                refchg = atomic_readandclear_32(&m->md.mdpg_attrs);
                                if (refchg & PTE_CHG)
                                        vm_page_dirty(m);
                                if (refchg & PTE_REF)
                                        vm_page_aflag_set(m, PGA_REFERENCED);
. . .

Note: So, if m is set above, then the next loop
iteration(s) would use this then-old value
instead of an initialized value.

It looks to me like at least one assignment
to m is missing.

moea64_pvo_protect has pg that seems analogous to
m and has:

        pg = PHYS_TO_VM_PAGE(pvo->pvo_pte.pa & LPTE_RPGN);
. . .
        if (pm != kernel_pmap && pg != NULL &&
            (pg->a.flags & PGA_EXECUTABLE) == 0 &&
            (pvo->pvo_pte.pa & (LPTE_I | LPTE_G | LPTE_NOEXEC)) == 0) {
                if ((pg->oflags & VPO_UNMANAGED) == 0)
                        vm_page_aflag_set(pg, PGA_EXECUTABLE);

. . .
        if (pg != NULL && (pvo->pvo_vaddr & PVO_MANAGED) &&
            (oldprot & VM_PROT_WRITE)) {
                refchg |= atomic_readandclear_32(&pg->md.mdpg_attrs);
                if (refchg & LPTE_CHG)
                        vm_page_dirty(pg);
                if (refchg & LPTE_REF)
                        vm_page_aflag_set(pg, PGA_REFERENCED);


This might suggest some about what is missing.


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)