PageAllocator: sometimes incorrect alignment when remapping to an alignment and size greater than page size

[NicoElbers]

Zig Version

0.14.0-dev.3241+55c46870b

Steps to Reproduce and Observed Behavior

mwe.zig:

pub fn main() !void {
    const alloc: Allocator = .{
        .ptr = undefined,
        .vtable = &std.heap.PageAllocator.vtable,
    };

    const alignment: Alignment = comptime .fromByteUnits(std.heap.page_size_min * 2);

    for (0..20_000) |size| {
        std.log.debug("size: {d}", .{size});
        var slice = try alloc.alignedAlloc(u8, alignment.toByteUnits(), 1);
        slice = alloc.remap(slice, size) orelse slice;

        alloc.free(slice);
    }
}

const std = @import("std");

const Allocator = std.mem.Allocator;
const Alignment = std.mem.Alignment;

run zig run mwe.zig

Observe:

...
debug: size: 8190
debug: size: 8191
debug: size: 8192
debug: size: 8193
thread 6940 panic: incorrect alignment
/nix/store/4h7cpfzzsczh6g8ivdvaz5k9dygy5z6p-zig-0.14.0-dev.3241+55c46870b/lib/std/mem/Allocator.zig:334:47: 0x103abd2 in remap__anon_2165 (mwe)
    const new_memory: []align(alignment) u8 = @alignCast(new_ptr[0..new_len_bytes]);
                                              ^
/home/nico/personal-projects/zig/alloc-bench/mwe.zig:12:28: 0x103a594 in main (mwe)
        slice = alloc.remap(slice, size) orelse slice;
                           ^
/nix/store/4h7cpfzzsczh6g8ivdvaz5k9dygy5z6p-zig-0.14.0-dev.3241+55c46870b/lib/std/start.zig:656:37: 0x103a3fa in posixCallMainAndExit (mwe)
            const result = root.main() catch |err| {
                                    ^
/nix/store/4h7cpfzzsczh6g8ivdvaz5k9dygy5z6p-zig-0.14.0-dev.3241+55c46870b/lib/std/start.zig:271:5: 0x1039fad in _start (mwe)
    asm volatile (switch (native_arch) {
    ^
???:?:?: 0x0 in ??? (???)
zsh: IOT instruction (core dumped)  zig run mwe.zig

Originally observed this with a size of 20_000

Not sure if it's relevant, but I'm on x86_64 linux

Expected Behavior

Allocator disallowing alignment greater than page_size_min as proposed in #7952 or correct alignment