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mm/execmem: handle potential allocation errors in the maple tree

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execmem_cache_clean() and execmem_cache_alloc_locked() ignore potential
allocation failures in mas_store_gfp().

While in practice they are unlikely to happen, it's better to handle those
errors and ensure the integrity of the ROX cache.

Preallocate the maple tree nodes for the stores that must not fail and
order the maple tree updates so that there won't be any failures once a
tree has been modified.

Link: https://lore.kernel.org/20260903-execmem-rox-cache-pmd-v1-v1-2-11beb2a3d249@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Assisted-by: copilot:claude-opus-5
Cc: Benjamin Tissoires <bentiss@kernel.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
This commit is contained in:
Mike Rapoport (Microsoft) 2026-09-03 18:49:59 +03:00 committed by Andrew Morton
parent 52d95a55a0
commit d80773cedd
1 changed files with 22 additions and 10 deletions
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32
mm/execmem.c
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@ -149,7 +149,15 @@ static void execmem_cache_clean(struct work_struct *work)
if (vm && get_vm_area_size(vm) == size &&
IS_ALIGNED(size, PMD_SIZE) &&
IS_ALIGNED(mas.index, PMD_SIZE)) {
mas_store_gfp(&mas, NULL, GFP_KERNEL);
/*
* Preallocate to ensure mas_store does not fail
* If there is no memory for the tree update, bail out,
* next execmem_free() might be more lucky
*/
if (mas_preallocate(&mas, NULL, GFP_KERNEL))
break;
mas_store_prealloc(&mas, NULL);
vfree(area);
}
}
@ -219,30 +227,34 @@ static void *execmem_cache_alloc_locked(struct execmem_range *range, size_t size
addr = mas_free.index;
last = mas_free.last;
mas_set_range(&mas_free, addr, addr + size - 1);
if (mas_preallocate(&mas_free, NULL, GFP_KERNEL))
return NULL;
/* insert allocated size to busy_areas at range [addr, addr + size) */
mas_set_range(&mas_busy, addr, addr + size - 1);
err = mas_store_gfp(&mas_busy, (void *)addr, GFP_KERNEL);
if (err)
return NULL;
goto err_destroy_mas_free;
mas_store_gfp(&mas_free, NULL, GFP_KERNEL);
mas_store_prealloc(&mas_free, NULL);
if (area_size > size) {
void *ptr = (void *)(addr + size);
/*
* re-insert remaining free size to free_areas at range
* [addr + size, last]
* the range matches an existing entry, so this cannot allocate
*/
ptr = (void *)(addr + size);
mas_set_range(&mas_free, addr + size, last);
err = mas_store_gfp(&mas_free, ptr, GFP_KERNEL);
if (err) {
mas_store_gfp(&mas_busy, NULL, GFP_KERNEL);
return NULL;
}
mas_store_gfp(&mas_free, ptr, GFP_KERNEL);
}
ptr = (void *)addr;
return ptr;
err_destroy_mas_free:
mas_destroy(&mas_free);
return NULL;
}
static void *__execmem_cache_alloc(struct execmem_range *range, size_t size)