diff --git a/lib/std/Io/test.zig b/lib/std/Io/test.zig
index 6af9a5bad98e3570e281ca6b346628411e567480..a467ee1a93992a32c460198e9de539fb1366df28 100644
--- a/lib/std/Io/test.zig
+++ b/lib/std/Io/test.zig
@@ -254,8 +254,6 @@ test "Group.cancel" {
 }
 
 test "Group.concurrent" {
-    if (builtin.os.tag == .linux and !builtin.link_libc) return error.SkipZigTest; // https://codeberg.org/ziglang/zig/issues/30096
-
     const io = testing.io;
 
     var group: Io.Group = .init;
@@ -421,8 +419,6 @@ test "Event" {
 }
 
 test "recancel" {
-    if (builtin.os.tag == .linux and !builtin.link_libc) return error.SkipZigTest; // https://codeberg.org/ziglang/zig/issues/30592
-
     const global = struct {
         fn worker(io: Io) Io.Cancelable!void {
             var dummy_event: Io.Event = .unset;
diff --git a/lib/std/Thread.zig b/lib/std/Thread.zig
index 126338e77f0a82eae15042c49a20c3155d677faf..1c361506b72e3eb1a8c6125642b68ba1e6fba51a 100644
--- a/lib/std/Thread.zig
+++ b/lib/std/Thread.zig
@@ -1224,6 +1224,10 @@ const LinuxThreadImpl = struct {
         /// Ported over from musl libc's pthread detached implementation:
         /// https://github.com/ifduyue/musl/search?q=__unmapself
         fn freeAndExit(self: *ThreadCompletion) noreturn {
+            // If a signal were delivered between SYS_munmap and SYS_exit, any installed signal
+            // handler would immediately segfault due to the stack being unmapped. To avoid this,
+            // we need to mask all signals before entering the inline asm.
+            posix.sigprocmask(std.posix.SIG.BLOCK, &std.os.linux.sigfillset(), null);
             switch (target.cpu.arch) {
                 .x86 => asm volatile (
                     \\  movl $91, %%eax # SYS_munmap
diff --git a/lib/std/crypto/argon2.zig b/lib/std/crypto/argon2.zig
index 2bb5a49a45feb4a0eeb59affaa612f94db6177e7..0fd76e1282ddf29f9426ee03696faede747769a6 100644
--- a/lib/std/crypto/argon2.zig
+++ b/lib/std/crypto/argon2.zig
@@ -907,8 +907,6 @@ test "kdf" {
 }
 
 test "phc format hasher" {
-    if (true) return error.SkipZigTest; // https://codeberg.org/ziglang/zig/issues/30682
-
     const allocator = std.testing.allocator;
     const password = "testpass";
     const io = std.testing.io;
diff --git a/lib/std/debug.zig b/lib/std/debug.zig
index 0f151447fc56b4d7afdde22709b2bc0fe414d554..8b76e307a154654c132b83480f5abf19f5243fcd 100644
--- a/lib/std/debug.zig
+++ b/lib/std/debug.zig
@@ -532,6 +532,10 @@ pub fn defaultPanic(msg: []const u8, first_trace_addr: ?usize) noreturn {
         else => {},
     }
 
+    // Don't try to cancel during a panic. No need to re-enable cancelation,
+    // because the panic handler doesn't return.
+    _ = std.Options.debug_io.swapCancelProtection(.blocked);
+
     if (enable_segfault_handler) {
         // If a segfault happens while panicking, we want it to actually segfault, not trigger
         // the handler.
@@ -1533,6 +1537,10 @@ fn handleSegfault(addr: ?usize, name: []const u8, opt_ctx: ?CpuContextPtr) noret
 }
 
 pub fn defaultHandleSegfault(addr: ?usize, name: []const u8, opt_ctx: ?CpuContextPtr) noreturn {
+    // Don't try to cancel during a segfault. No need to re-enable cancelation,
+    // because the segfault handler doesn't return.
+    _ = std.Options.debug_io.swapCancelProtection(.blocked);
+
     // There is very similar logic to the following in `defaultPanic`.
     switch (panic_stage) {
         0 => {