Messages in this thread Patch in this message | | | Date | Mon, 12 Feb 2024 13:37:09 -0800 | From | Tony Luck <> | Subject | Re: [PATCH 2/2] x86/MCE: Add command line option to extend MCE Records pool |
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On Mon, Feb 12, 2024 at 07:41:03PM +0000, Luck, Tony wrote: > > It needs a proper explanation why that's ok rather than an empirical > > test only. > > start_kernel() > ... setup_arch() > .... acpi stuff parses MADT and sets bits in possible map > > ... arch_cpu_finalize_init() > ... calls mce_gen_pool_init()
This made me question the "we don't have an allocator in mce_gen_pool_init()". Because if we got through all the ACPI stuff, we surely have an allocator.
Below patch doesn't explode at runtime.
-Tony
diff --git a/arch/x86/kernel/cpu/mce/genpool.c b/arch/x86/kernel/cpu/mce/genpool.c index fbe8b61c3413..81de877f2a51 100644 --- a/arch/x86/kernel/cpu/mce/genpool.c +++ b/arch/x86/kernel/cpu/mce/genpool.c @@ -16,14 +16,12 @@ * used to save error information organized in a lock-less list. * * This memory pool is only to be used to save MCE records in MCE context. - * MCE events are rare, so a fixed size memory pool should be enough. Use - * 2 pages to save MCE events for now (~80 MCE records at most). + * MCE events are rare, so a fixed size memory pool should be enough. + * Allocate on a sliding scale based on number of CPUs. */ -#define MCE_POOLSZ (2 * PAGE_SIZE) static struct gen_pool *mce_evt_pool; static LLIST_HEAD(mce_event_llist); -static char gen_pool_buf[MCE_POOLSZ]; /* * Compare the record "t" with each of the records on list "l" to see if @@ -118,14 +116,23 @@ int mce_gen_pool_add(struct mce *mce) static int mce_gen_pool_create(void) { + int mce_numrecords, mce_poolsz; struct gen_pool *tmpp; int ret = -ENOMEM; + void *mce_pool; tmpp = gen_pool_create(ilog2(sizeof(struct mce_evt_llist)), -1); if (!tmpp) goto out; - ret = gen_pool_add(tmpp, (unsigned long)gen_pool_buf, MCE_POOLSZ, -1); + mce_numrecords = max(80, num_possible_cpus() * 8); + mce_poolsz = mce_numrecords * ilog2(sizeof(struct mce_evt_llist)); + mce_pool = kmalloc(mce_poolsz, GFP_KERNEL); + if (!mce_pool) { + gen_pool_destroy(tmpp); + goto out; + } + ret = gen_pool_add(tmpp, (unsigned long)mce_pool, mce_poolsz, -1); if (ret) { gen_pool_destroy(tmpp); goto out; -- 2.43.0
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