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Kernel: Make kmalloc expansions scale to incoming allocation request

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This allows kmalloc() to satisfy arbitrary allocation requests instead
of being limited to a static subheap expansion size.
This commit is contained in:
Andreas Kling 2021-12-26 10:40:28 +01:00
parent f49649645c
commit 1c99f99e99
Notes: sideshowbarker 2024-07-17 22:10:47 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/1c99f99e995
1 changed files with 13 additions and 3 deletions
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16
Kernel/Heap/kmalloc.cpp
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@ -48,6 +48,8 @@ struct KmallocSubheap {
};
struct KmallocGlobalData {
static constexpr size_t minimum_subheap_size = 1 * MiB;
KmallocGlobalData(u8* initial_heap, size_t initial_heap_size)
{
add_subheap(initial_heap, initial_heap_size);
@ -69,7 +71,7 @@ struct KmallocGlobalData {
return ptr;
}
if (!try_expand()) {
if (!try_expand(size)) {
PANIC("OOM when trying to expand kmalloc heap.");
}
@ -106,13 +108,21 @@ struct KmallocGlobalData {
return total;
}
bool try_expand()
bool try_expand(size_t allocation_request)
{
VERIFY(!expansion_in_progress);
TemporaryChange change(expansion_in_progress, true);
auto new_subheap_base = expansion_data->next_virtual_address;
size_t new_subheap_size = 1 * MiB;
Checked<size_t> padded_allocation_request = allocation_request;
padded_allocation_request *= 2;
padded_allocation_request += PAGE_SIZE;
if (padded_allocation_request.has_overflow()) {
PANIC("Integer overflow during kmalloc heap expansion");
}
size_t new_subheap_size = max(minimum_subheap_size, Memory::page_round_up(padded_allocation_request.value()));
dbgln("Unable to allocate {}, expanding kmalloc heap", allocation_request);
if (!expansion_data->virtual_range.contains(new_subheap_base, new_subheap_size)) {
// FIXME: Dare to return false and allow kmalloc() to fail!