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kernel/vm: Make privately-mapped anonymous regions avoid committing memory too.

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This was already the case for non-anonymous regions (i.e. mmap'ed files),
but wasn't the case for anonymous ones (fd < 0). Now it is.
This commit is contained in:
Augustin Cavalier
2024-12-10 22:34:16 -05:00
parent 5b2ecc7859
commit 3cd8a6719d
1 changed files with 6 additions and 5 deletions
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src/system/kernel/vm/vm.cpp
+6 -5
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@@ -2271,6 +2271,12 @@ _vm_map_file(team_id team, const char* name, void** _address,
uint32 mappingFlags = 0;
if (unmapAddressRange)
mappingFlags |= CREATE_AREA_UNMAP_ADDRESS_RANGE;
if (mapping == REGION_PRIVATE_MAP) {
// For privately mapped read-only regions, skip committing memory.
// (If protections are changed later on, memory will be committed then.)
if ((protection & (B_WRITE_AREA | B_KERNEL_WRITE_AREA)) == 0)
mappingFlags |= CREATE_AREA_DONT_COMMIT_MEMORY;
}
if (fd < 0) {
virtual_address_restrictions virtualRestrictions = {};
@@ -2304,11 +2310,6 @@ _vm_map_file(team_id team, const char* name, void** _address,
protectionMax = protection | B_USER_PROTECTION;
else
protectionMax = protection | (B_USER_PROTECTION & ~B_WRITE_AREA);
} else if (mapping == REGION_PRIVATE_MAP) {
// For privately mapped read-only regions, skip committing memory.
// (If protections are changed later on, memory will be committed then.)
if ((protection & B_WRITE_AREA) == 0)
mappingFlags |= CREATE_AREA_DONT_COMMIT_MEMORY;
}
// get the vnode for the object, this also grabs a ref to it