linux-kernel - Re: [PATCH 4/4] memblock: stop poisoning raw allocations

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Date:   Tue, 3 Aug 2021 10:58:42 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Joe Perches <joe@...ches.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Simek <monstr@...str.eu>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 4/4] memblock: stop poisoning raw allocations

On Sat, Jul 31, 2021 at 10:13:04AM -0700, Joe Perches wrote:
> On Wed, 2021-07-14 at 15:37 +0300, Mike Rapoport wrote:
> > From: Mike Rapoport <rppt@...ux.ibm.com>
> > 
> > Functions memblock_alloc_exact_nid_raw() and memblock_alloc_try_nid_raw()
> > are intended for early memory allocation without overhead of zeroing the
> > allocated memory. Since these functions were used to allocate the memory
> > map, they have ended up with addition of a call to page_init_poison() that
> > poisoned the allocated memory when CONFIG_PAGE_POISON was set.
> > 
> > Since the memory map is allocated using a dedicated memmep_alloc() function
> > that takes care of the poisoning, remove page poisoning from the
> > memblock_alloc_*_raw() functions.
> []
> > diff --git a/mm/memblock.c b/mm/memblock.c
> []
> > @@ -1490,18 +1490,12 @@ void * __init memblock_alloc_exact_nid_raw(
> >  			phys_addr_t min_addr, phys_addr_t max_addr,
> >  			int nid)
> >  {
> > -	void *ptr;
> > -
> >  	memblock_dbg("%s: %llu bytes align=0x%llx nid=%d from=%pa max_addr=%pa %pS\n",
> >  		     __func__, (u64)size, (u64)align, nid, &min_addr,
> >  		     &max_addr, (void *)_RET_IP_);
> 
> unassociated trivia:
> 
> casting _RET_IP_ back to void * seems odd as the define is
> include/linux/kernel.h:#define _RET_IP_         (unsigned long)__builtin_return_address(0)
> 
> It's probably easier to understand as just __builtin_return_address(0)

Maybe, but I'm not sure it's worth the churn.
 
> > @@ -1528,18 +1522,12 @@ void * __init memblock_alloc_try_nid_raw(
> >  			phys_addr_t min_addr, phys_addr_t max_addr,
> >  			int nid)
> >  {
> > -	void *ptr;
> > -
> >  	memblock_dbg("%s: %llu bytes align=0x%llx nid=%d from=%pa max_addr=%pa %pS\n",
> >  		     __func__, (u64)size, (u64)align, nid, &min_addr,
> >  		     &max_addr, (void *)_RET_IP_);
> 
> here too
> 

-- 
Sincerely yours,
Mike.