Re: [PATCH 1/2] kfence: allow providing __kfence_pool in arch specific way
From: Marco Elver <elver@google.com>
Date: 2021-05-24 10:36:52
Also in:
linux-mm, lkml
On Mon, 24 May 2021 at 11:26, Jisheng Zhang [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Some architectures may want to allocate the __kfence_pool differently for example, allocate the __kfence_pool earlier before paging_init(). We also delay the memset() to kfence_init_pool(). Signed-off-by: Jisheng Zhang <redacted> --- mm/kfence/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)diff --git a/mm/kfence/core.c b/mm/kfence/core.c index e18fbbd5d9b4..65f0210edb65 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c@@ -430,6 +430,8 @@ static bool __init kfence_init_pool(void) if (!__kfence_pool) return false; + memset(__kfence_pool, 0, KFENCE_POOL_SIZE); +
Use memzero_explicit(). Also, for the arm64 case, is delaying the zeroing relevant? You still call kfence_alloc_pool() in patch 2/2, and zeroing it on memblock_alloc() is not wrong, correct? Essentially if there's not going to be any benefit to us doing the zeroing ourselves, I'd simply leave it as-is and keep using memblock_alloc(). And if there's some odd architecture that doesn't even want to use kfence_alloc_pool(), they could just zero the memory themselves. But we really should use kfence_alloc_pool(), because otherwise it'll just become unmaintainable if on changes to kfence_alloc_pool() we have to go and find other special architectures that don't use it and adjust them, too. Thanks, -- Marco
quoted hunk ↗ jump to hunk
if (!arch_kfence_init_pool()) goto err;@@ -645,10 +647,10 @@ static DECLARE_DELAYED_WORK(kfence_timer, toggle_allocation_gate); void __init kfence_alloc_pool(void) { - if (!kfence_sample_interval) + if (!kfence_sample_interval || __kfence_pool) return; - __kfence_pool = memblock_alloc(KFENCE_POOL_SIZE, PAGE_SIZE); + __kfence_pool = memblock_alloc_raw(KFENCE_POOL_SIZE, PAGE_SIZE); if (!__kfence_pool) pr_err("failed to allocate pool\n"); --2.31.0
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