This commit fixes the following panic when running nodejs:
```
KERNEL PANIC: panicked at src/context/memory.rs:267:18:
grant cannot magically disappear while we hold the lock!
FP ffff80002021f650: PC ffffffff8005e45b
FFFFFFFF8005E2E0+017B
kernel::panic::panic_handler_inner
FP ffff80002021f730: PC ffffffff80057559
FP ffff80002021f740: PC ffffffff8009a0ff
FP ffff80002021f770: PC ffffffff8009c214
FP ffff80002021f7d0: PC ffffffff80010997
FFFFFFFF8000FDD0+0BC7
kernel::context::memory::AddrSpaceWrapper::mprotect
FP ffff80002021fd40: PC ffffffff8008cb0b
FFFFFFFF8008CA40+00CB
kernel::syscall::process::mprotect
FP ffff80002021fd70: PC ffffffff8006ce6c
FFFFFFFF8006CBE0+028C
kernel::syscall::syscall
FP ffff80002021fe90: PC ffffffff8008d3cf
FFFFFFFF8008D320+00AF
__inner_syscall_instruction
FP ffff80002021ff50: PC ffffffff800830c3
FFFFFFFF80083080+0043
kernel::arch::x86_64::interrupt::syscall::syscall_instruction
00007ffffffffaf0: GUARD PAGE
CPU #1, CID 0xffffff7f8015b910
NAME: /usr/bin/node, DEBUG ID: 74
SYSCALL: mprotect(0x203C0000, 262144, Some(MapFlags(0x0)))
HALT
```
The grant did not magically disappear. When going through the
`grant_span_res` regions, the function adds (and removes) grants to the
`self.grants` tree. The insertion and deletion functions also merge
adjacent grants together when possible. This is an issue since we can no
longer use the keys we established before we started iterating. This
commit modifies the places where `remove` is used in this fashion to use
`remove_containing` instead. The `remove_containing` function will
remove the grant that *contains* the page.
Should it be done this way (requires unstable feature `btree_cursors`)?
Signed-off-by: Anhad Singh <andypython@protonmail.com>
Anhad Singh
a8699a7e72