Re: Still seeing Failed assertion: "p[i] == 0" on armv7 buildworld [Notes from another example core dump: #5] [Common range #0..#10 __je_pa_alloc]

On Nov 18, 2025, at 22:10, Mark Millard <[email protected]> wrote:

> I'm only sending notes from testing of how similar other failures appear
> to the 2 lists. Folks can ask that I do otherwise for them if they want.
> 
> This one also does not have area_malloc involved at all.
> 
> This one is for size 8192 (2 pages). It looks like #0..#10 are similar to
> the prior reports. #10 is __je_pa_alloc.
> 
> #11 is: arena_slab_alloc
> 
> (gdb) bt
> #0  thr_kill () at thr_kill.S:4
> #1  0x2a08ef24 in __raise (s=6) at /usr/src/lib/libc/gen/raise.c:48
> #2  0x2a145f38 in abort () at /usr/src/lib/libc/stdlib/abort.c:61
> #3  0x2a196128 in ehooks_debug_zero_check (addr=addr@entry=0x2e12b000, size=size@entry=8192) at /usr/src/contrib/jemalloc/include/jemalloc/internal/ehooks.h:170
> #4  0x2a191f60 in ehooks_alloc (tsdn=0x2a2e4060, ehooks=0x2a600080, new_addr=0x0, size=<optimized out>, alignment=4096, zero=0xffff9747, commit=<optimized out>)
>    at /usr/src/contrib/jemalloc/include/jemalloc/internal/ehooks.h:208
> #5  __je_extent_alloc_wrapper (tsdn=tsdn@entry=0x2a2e4060, pac=0x2a601810, ehooks=<optimized out>, new_addr=<optimized out>, size=8192, alignment=4096, zero=true, commit=0xffff97a7, 
>    growing_retained=<optimized out>) at jemalloc_extent.c:1003
> #6  0x2a1916e0 in __je_ecache_alloc_grow (tsdn=<optimized out>, tsdn@entry=0x2a2e4060, pac=pac@entry=0x2a601810, ehooks=ehooks@entry=0x2a600080, ecache=<optimized out>, ecache@entry=0x2a603dd0, 
>    expand_edata=0x0, size=8192, alignment=4096, zero=<optimized out>, guarded=<optimized out>) at jemalloc_extent.c:126
> #7  0x2a1c9680 in pac_alloc_real (tsdn=0x2a2e4060, pac=0x2a601810, ehooks=0x2a600080, size=8192, alignment=4096, zero=<optimized out>, guarded=false) at jemalloc_pac.c:124
> #8  pac_alloc_impl (tsdn=tsdn@entry=0x2a2e4060, self=0x2a601810, size=size@entry=8192, alignment=4096, zero=<optimized out>, guarded=false, frequent_reuse=<optimized out>, 
>    deferred_work_generated=<optimized out>) at jemalloc_pac.c:178
> #9  0x2a1c7ae8 in pai_alloc (tsdn=0x2a2e4060, self=0x0, size=8192, alignment=2147483615, zero=<optimized out>, guarded=false, frequent_reuse=true, deferred_work_generated=<optimized out>)
>    at /usr/src/contrib/jemalloc/include/jemalloc/internal/pai.h:43
> #10 __je_pa_alloc (tsdn=tsdn@entry=0x2a2e4060, shard=shard@entry=0x2a601800, size=8192, alignment=<optimized out>, slab=true, szind=35, zero=<optimized out>, guarded=false, 
>    deferred_work_generated=0xffff986f) at jemalloc_pa.c:139
> #11 0x2a16b9f8 in arena_slab_alloc (tsdn=tsdn@entry=0x2a2e4060, arena=0x2a600540, binind=35, binshard=0, bin_info=0x2a2200ec <__je_bin_infos+1680>) at jemalloc_arena.c:839
> #12 0x2a16ac98 in __je_arena_cache_bin_fill_small (tsdn=0x2a2e4060, arena=0x2a600540, cache_bin=cache_bin@entry=0x2a2e4618, cache_bin_info=0x2a600506, binind=35, nfill=10) at jemalloc_arena.c:1034
> #13 0x2a1b5694 in __je_tcache_alloc_small_hard (tsdn=0x0, tsdn@entry=0x2a2e4060, arena=0x0, arena@entry=0x2a600540, tcache=tcache@entry=0x2a2e42c8, cache_bin=cache_bin@entry=0x2a2e4618, binind=35, 
>    tcache_success=0xffff991f) at jemalloc_tcache.c:238
> #14 0x2a16cef4 in tcache_alloc_small (tsd=<optimized out>, arena=0x2a600540, tcache=0x2a2e42c8, size=<optimized out>, binind=35, zero=false, slow_path=true)
>    at /usr/src/contrib/jemalloc/include/jemalloc/internal/tcache_inlines.h:68
> #15 arena_malloc (tsdn=<optimized out>, arena=<optimized out>, size=8192, ind=35, zero=false, tcache=0x2a2e42c8, slow_path=true)
>    at /usr/src/contrib/jemalloc/include/jemalloc/internal/arena_inlines_b.h:151
> #16 0x2a16cb88 in __je_arena_palloc (tsdn=0x0, tsdn@entry=0x2a2e4060, arena=<optimized out>, usize=<optimized out>, usize@entry=8192, alignment=alignment@entry=8, zero=false, tcache=0x2a2e42c8)
>    at jemalloc_arena.c:1224
> #17 0x2a16559c in ipallocztm (tsdn=0x2a2e4060, tsdn@entry=0x2a2e42c8, usize=8192, alignment=8, zero=false, tcache=0x2a2e42c8, is_internal=false, arena=0x0)
>    at /usr/src/contrib/jemalloc/include/jemalloc/internal/jemalloc_internal_inlines_c.h:80
> #18 ipalloct (tsdn=0x0, tsdn@entry=0x2a2e4060, usize=8192, alignment=8, zero=false, tcache=0x2a2e42c8, arena=0x0)
>    at /usr/src/contrib/jemalloc/include/jemalloc/internal/jemalloc_internal_inlines_c.h:91
> #19 0x2a1651f4 in imalloc_no_sample (sopts=0xffff9a14, dopts=0xffff99f4, tsd=0x2a2e4060, size=8192, usize=8192, ind=<optimized out>) at jemalloc_jemalloc.c:2398
> #20 imalloc_body (sopts=0xffff9a14, dopts=0xffff99f4, tsd=0x2a2e4060) at jemalloc_jemalloc.c:2577
> #21 0x2a156188 in imalloc (sopts=sopts@entry=0xffff9a14, dopts=<optimized out>, dopts@entry=0xffff99f4) at jemalloc_jemalloc.c:2693
> #22 0x2a15677c in __aligned_alloc (alignment=8, size=8192) at jemalloc_jemalloc.c:2821
> #23 0x29e61a00 in std::__1::__libcpp_aligned_alloc[abi:se190107](unsigned int, unsigned int) (__alignment=8, __size=<optimized out>)
>    at /usr/src/contrib/llvm-project/libcxx/include/__memory/aligned_alloc.h:43
> #24 operator_new_aligned_impl (size=<optimized out>, alignment=8) at /usr/src/contrib/llvm-project/libcxx/src/new.cpp:129
> #25 operator new (size=<optimized out>, alignment=<optimized out>) at /usr/src/contrib/llvm-project/libcxx/src/new.cpp:141
> #26 0x20ff35f8 in Allocate () at /usr/src/contrib/llvm-project/llvm/include/llvm/Support/AllocatorBase.h:92
> #27 StartNewSlab () at /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Allocator.h:344
> #28 AllocateSlow () at /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Allocator.h:200
> #29 0x26c0ab48 in Allocate () at /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Allocator.h:176
> #30 Allocate () at /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Allocator.h:214
> #31 operator new<llvm::MallocAllocator, 4096U, 4096U, 128U> () at /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Allocator.h:448
> #32 getMachineMemOperand () at /usr/src/contrib/llvm-project/llvm/lib/CodeGen/MachineFunction.cpp:496
> #33 0x2705c62c in getStore () at /usr/src/contrib/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:9015
> #34 0x270941b4 in visitStore () at /usr/src/contrib/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp:4746
> #35 0x2708d80c in visit () at /usr/src/contrib/llvm-project/llvm/include/llvm/IR/Instruction.def:173
> #36 0x2708c9e4 in visit () at /usr/src/contrib/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp:1346
> #37 0x270f53c8 in SelectBasicBlock () at /usr/src/contrib/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:838
> #38 0x270f4b84 in SelectAllBasicBlocks () at /usr/src/contrib/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1863
> #39 0x270f1f24 in runOnMachineFunction () at /usr/src/contrib/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:631
> #40 0x28300224 in runOnMachineFunction () at /usr/src/contrib/llvm-project/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp:70
> #41 0x270efd6c in runOnMachineFunction () at /usr/src/contrib/llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:374
> #42 0x26c15e88 in runOnFunction () at /usr/src/contrib/llvm-project/llvm/lib/CodeGen/MachineFunctionPass.cpp:94
> #43 0x276a9e74 in runOnFunction () at /usr/src/contrib/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1440
> #44 0x276b0d40 in runOnModule () at /usr/src/contrib/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1486
> #45 0x276aa5e0 in runOnModule () at /usr/src/contrib/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1555
> --Type <RET> for more, q to quit, c to continue without paging--
> #46 run () at /usr/src/contrib/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:541
> #47 0x2216d2e8 in RunCodegenPipeline () at /usr/src/contrib/llvm-project/clang/lib/CodeGen/BackendUtil.cpp:1157
> #48 EmitAssembly () at /usr/src/contrib/llvm-project/clang/lib/CodeGen/BackendUtil.cpp:1180
> #49 EmitBackendOutput () at /usr/src/contrib/llvm-project/clang/lib/CodeGen/BackendUtil.cpp:1341
> #50 0x225cbca0 in HandleTranslationUnit () at /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenAction.cpp:354
> #51 0x22cff8e4 in ParseAST () at /usr/src/contrib/llvm-project/clang/lib/Parse/ParseAST.cpp:184
> #52 0x22b5a7b8 in Execute () at /usr/src/contrib/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1078
> #53 0x22adb800 in ExecuteAction () at /usr/src/contrib/llvm-project/clang/lib/Frontend/CompilerInstance.cpp:1061
> #54 0x22bf6a90 in ExecuteCompilerInvocation () at /usr/src/contrib/llvm-project/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:280
> #55 0x0002afc8 in cc1_main () at /usr/src/contrib/llvm-project/clang/tools/driver/cc1_main.cpp:284
> #56 0x00038548 in ExecuteCC1Tool () at /usr/src/contrib/llvm-project/clang/tools/driver/driver.cpp:215
> #57 0x227877ec in operator() () at /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:68
> #58 operator() () at /usr/src/contrib/llvm-project/clang/lib/Driver/Job.cpp:440
> #59 callback_fn<(lambda at /usr/src/contrib/llvm-project/clang/lib/Driver/Job.cpp:440:22)>(void) () at /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:45
> #60 0x27d88624 in operator() () at /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/STLFunctionalExtras.h:68
> #61 RunSafely () at /usr/src/contrib/llvm-project/llvm/lib/Support/CrashRecoveryContext.cpp:426
> #62 0x22786e90 in Execute () at /usr/src/contrib/llvm-project/clang/lib/Driver/Job.cpp:440
> #63 0x22748074 in ExecuteCommand () at /usr/src/contrib/llvm-project/clang/lib/Driver/Compilation.cpp:199
> #64 0x227483d0 in ExecuteJobs () at /usr/src/contrib/llvm-project/clang/lib/Driver/Compilation.cpp:253
> #65 0x22765bb8 in ExecuteCompilation () at /usr/src/contrib/llvm-project/clang/lib/Driver/Driver.cpp:1943
> #66 0x00037ba4 in clang_main () at /usr/src/contrib/llvm-project/clang/tools/driver/driver.cpp:391
> #67 0x000363a8 in main () at /usr/src/usr.bin/clang/clang/clang-driver.cpp:17
> 
> 
> 
> 0x2e12afd0: 0xa5a5a5a5 0xa5a5a5a5 0xa5a5a5a5 0xa5a5a5a5
> 0x2e12afe0: 0xa5a5a5a5 0xa5a5a5a5 0xa5a5a5a5 0xa5a5a5a5
> 0x2e12aff0: 0xa5a5a5a5 0xa5a5a5a5 0xa5a5a5a5 0xa5a5a5a5
> (gdb) x /1024x ((size_t*)addr)+0
> 0x2e12b000: 0x00000000 0x00000000 0x00000000 0x00000000
> 0x2e12b010: 0x00000000 0x00000000 0x00000000 0x00000000
> 0x2e12b020: 0x00000000 0x00000000 0x00000000 0x00000000
> . . .
> 0x2e12b650: 0x00000000 0x00000000 0x00000000 0x00000000
> 0x2e12b660: 0x00000000 0x00000000 0x00000000 0x00000000
> 0x2e12b670: 0x00000000 0x00000000 0x00000000 0x00000000
> 0x2e12b680: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a
> 0x2e12b690: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a
> 0x2e12b6a0: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a
> . . .
> 0x2e12cfd0: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a
> 0x2e12cfe0: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a
> 0x2e12cff0: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a
> (gdb) x /1024x ((size_t*)addr)+2048
> 0x2e12d000: Cannot access memory at address 0x2e12d000
> 
> 
> 
> For #0..#10: The prior examples and the above
> agree about:
> 
> #5  __je_extent_alloc_wrapper zero=true
> 
> But also there was in this example:
> #14 tcache_alloc_small        zero=false
> 
> (The others before #14 are optimized out.)
> 
> 
> So summarizing some of the failure results so far . . .
> 
> The common part of the call chain is:
> 
> #0  thr_kill ()               at thr_kill.S:4
> #1  __raise (s=6)             at /usr/src/lib/libc/gen/raise.c:48
> #2  abort ()                  at /usr/src/lib/libc/stdlib/abort.c:61
> #3  ehooks_debug_zero_check   at /usr/src/contrib/jemalloc/include/jemalloc/internal/ehooks.h:170
> #4  ehooks_alloc              at /usr/src/contrib/jemalloc/include/jemalloc/internal/ehooks.h:208
> #5  __je_extent_alloc_wrapper at jemalloc_extent.c:1003 (argument zero=true)
> #6  __je_ecache_alloc_grow    at jemalloc_extent.c:126
> #7  pac_alloc_real            at jemalloc_pac.c:124
> #8  pac_alloc_impl            at jemalloc_pac.c:178
> #9  pai_alloc                 at /usr/src/contrib/jemalloc/include/jemalloc/internal/pai.h:43
> #10 __je_pa_alloc             at jemalloc_pa.c:139
> Note: some #11+ can show arguments with a zero=false
> 
> All the non-zero Bytes in the pages being checked are 0x5a bytes.
> The zero Bytes (if any) come first so far.

By no means do I know if the below is the actual problem.


The one place I see zero possibly becoming true for
__je_extent_alloc_wrapper by the time of the backtrace
is via:

void *
extent_alloc_mmap(void *new_addr, size_t size, size_t alignment, bool *zero,
    bool *commit) {
        assert(alignment == ALIGNMENT_CEILING(alignment, PAGE));
        void *ret = pages_map(new_addr, size, alignment, commit);
        if (ret == NULL) {
                return NULL;
        }
        assert(ret != NULL);
        if (*commit) {
                *zero = true;
        }
        return ret;
}

(So pages_map behavior vs. commit usage is relevant.
See jemalloc/src/pages.c .)

extent_alloc_mmap called via:

/*
 * If the caller specifies (!*zero), it is still possible to receive zeroed
 * memory, in which case *zero is toggled to true.  arena_extent_alloc() takes
 * advantage of this to avoid demanding zeroed extents, but taking advantage of
 * them if they are returned.
 */
static void *
extent_alloc_core(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size,
    size_t alignment, bool *zero, bool *commit, dss_prec_t dss_prec) {
        void *ret;

        assert(size != 0);
        assert(alignment != 0);

        /* "primary" dss. */
        if (have_dss && dss_prec == dss_prec_primary && (ret =
            extent_alloc_dss(tsdn, arena, new_addr, size, alignment, zero,
            commit)) != NULL) {
                return ret;
        }
        /* mmap. */
        if ((ret = extent_alloc_mmap(new_addr, size, alignment, zero, commit))
            != NULL) {
                return ret;
        }
        /* "secondary" dss. */
        if (have_dss && dss_prec == dss_prec_secondary && (ret =
            extent_alloc_dss(tsdn, arena, new_addr, size, alignment, zero,
            commit)) != NULL) {
                return ret;
        }

        /* All strategies for allocation failed. */
        return NULL;
}

in jemalloc/src/ehooks.c

called via:

void *
ehooks_default_alloc_impl(tsdn_t *tsdn, void *new_addr, size_t size,
    size_t alignment, bool *zero, bool *commit, unsigned arena_ind) {
        arena_t *arena = arena_get(tsdn, arena_ind, false);
        /* NULL arena indicates arena_create. */
        assert(arena != NULL || alignment == HUGEPAGE);
        dss_prec_t dss = (arena == NULL) ? dss_prec_disabled :
            (dss_prec_t)atomic_load_u(&arena->dss_prec, ATOMIC_RELAXED);
        void *ret = extent_alloc_core(tsdn, arena, new_addr, size, alignment,
            zero, commit, dss);
        if (have_madvise_huge && ret) {
                pages_set_thp_state(ret, size);
        }
        return ret;
}

in jemalloc/src/ehooks.c

called via (so is ehooks_debug_zero_check):

static inline void *
ehooks_alloc(tsdn_t *tsdn, ehooks_t *ehooks, void *new_addr, size_t size,
    size_t alignment, bool *zero, bool *commit) {
        bool orig_zero = *zero;
        void *ret;
        extent_hooks_t *extent_hooks = ehooks_get_extent_hooks_ptr(ehooks);
        if (extent_hooks == &ehooks_default_extent_hooks) {
                ret = ehooks_default_alloc_impl(tsdn, new_addr, size,
                    alignment, zero, commit, ehooks_ind_get(ehooks));
        } else {
                ehooks_pre_reentrancy(tsdn);
                ret = extent_hooks->alloc(extent_hooks, new_addr, size,
                    alignment, zero, commit, ehooks_ind_get(ehooks));
                ehooks_post_reentrancy(tsdn);
        }
        assert(new_addr == NULL || ret == NULL || new_addr == ret);
        assert(!orig_zero || *zero);
        if (*zero && ret != NULL) {
                ehooks_debug_zero_check(ret, size);
        }
        return ret;
}

called via:

edata_t *
extent_alloc_wrapper(tsdn_t *tsdn, pac_t *pac, ehooks_t *ehooks,
    void *new_addr, size_t size, size_t alignment, bool zero, bool *commit,
    bool growing_retained) {
        witness_assert_depth_to_rank(tsdn_witness_tsdp_get(tsdn),
            WITNESS_RANK_CORE, growing_retained ? 1 : 0);

        edata_t *edata = edata_cache_get(tsdn, pac->edata_cache);
        if (edata == NULL) {
                return NULL;
        }
        size_t palignment = ALIGNMENT_CEILING(alignment, PAGE);
        void *addr = ehooks_alloc(tsdn, ehooks, new_addr, size, palignment,
            &zero, commit);
. . .

===
Mark Millard
marklmi at yahoo.com