| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Thu, 1 Sep 2022 16:14:39 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Michal Hocko <mhocko@...e.com>, linux-mm@...ck.org
Cc: Christoph Hellwig <hch@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Mel Gorman <mgorman@...e.de>,
Johannes Weiner <hannes@...xchg.org>,
Dan Carpenter <dan.carpenter@...cle.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] mm: reduce noise in show_mem for lowmem allocations
On 8/30/22 09:34, Michal Hocko wrote:
> [Cc Dan]
> Dan has brought up[1] that the use of gfp mask has confused his static
> analyzer which assumes that GFP_HIGHUSER_MOVABLE implies a sleeping
> allocation and that wouldn't be a great idea from the panic path. I
> would add that most callers of this function would be really bad to
> allocate.
>
> The report itself is a false positive but it made me think a bit about
> this. Even if the check is too simplistic I guess it resembles how many
> developers are thinking (including me). If I see GFP_HIGHUSER_MOVABLE or
> GF_KERNEL I automatically assume a sleeping allocation down the road.
> And who know somebody might add one in the future even into show_mem
> because the gfp parameter would be too tempting to not (ab)use.
>
> My original intention was to use a natural allocation speak but this can
> backfire so maybe it would be better to give the argument its real
> meaning and that is the high_zone_idx. This is cryptic for code outside
> of MM but that is not all that many callers and we can hide this fact
> from them. In other words does the thing below looks better (incremental
> for illustration, I will make it a proper patch if yes)?
Yeah, looks better to me this way. Thanks!
>
> [1] https://lore.kernel.org/all/Yw2ugrlZ8bwE5/hh@kili/?q=http%3A%2F%2Flkml.kernel.org%2Fr%2FYw2ugrlZ8bwE5%2Fhh%40kili
>
> ---
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index 19b1a94b0c00..3d9782ea3fa7 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -1086,7 +1086,7 @@ cmds(struct pt_regs *excp)
> memzcan();
> break;
> case 'i':
> - show_mem(0, NULL, GFP_HIGHUSER_MOVABLE);
> + show_mem(0, NULL);
> break;
> default:
> termch = cmd;
> diff --git a/arch/sparc/kernel/setup_32.c b/arch/sparc/kernel/setup_32.c
> index 2a1e5641a7cc..c8e0dd99f370 100644
> --- a/arch/sparc/kernel/setup_32.c
> +++ b/arch/sparc/kernel/setup_32.c
> @@ -83,7 +83,7 @@ static void prom_sync_me(void)
> "nop\n\t" : : "r" (&trapbase));
>
> prom_printf("PROM SYNC COMMAND...\n");
> - show_free_areas(0, NULL, GFP_HIGHUSER_MOVABLE);
> + show_free_areas(0, NULL);
> if (!is_idle_task(current)) {
> local_irq_enable();
> ksys_sync();
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> index c6b2b42d2367..d2b2720db6ca 100644
> --- a/drivers/tty/sysrq.c
> +++ b/drivers/tty/sysrq.c
> @@ -342,7 +342,7 @@ static const struct sysrq_key_op sysrq_ftrace_dump_op = {
>
> static void sysrq_handle_showmem(int key)
> {
> - show_mem(0, NULL, GFP_HIGHUSER_MOVABLE);
> + show_mem(0, NULL);
> }
> static const struct sysrq_key_op sysrq_showmem_op = {
> .handler = sysrq_handle_showmem,
> diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
> index 9ceeea531cf6..be8313cdbac3 100644
> --- a/drivers/tty/vt/keyboard.c
> +++ b/drivers/tty/vt/keyboard.c
> @@ -606,7 +606,7 @@ static void fn_scroll_back(struct vc_data *vc)
>
> static void fn_show_mem(struct vc_data *vc)
> {
> - show_mem(0, NULL, GFP_HIGHUSER_MOVABLE);
> + show_mem(0, NULL);
> }
>
> static void fn_show_state(struct vc_data *vc)
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index e0d0ac52770c..0756798feaff 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1827,7 +1827,11 @@ extern void pagefault_out_of_memory(void);
> */
> #define SHOW_MEM_FILTER_NODES (0x0001u) /* disallowed nodes */
>
> -extern void show_free_areas(unsigned int flags, nodemask_t *nodemask, gfp_t gfp_mask);
> +extern void __show_free_areas(unsigned int flags, nodemask_t *nodemask, int max_zone_idx);
> +static void __maybe_unused show_free_areas(unsigned int flags, nodemask_t *nodemask)
> +{
> + __show_free_areas(flags, nodemask, MAX_NR_ZONES - 1);
> +}
>
> #ifdef CONFIG_MMU
> extern bool can_do_mlock(void);
> @@ -2563,7 +2567,12 @@ extern void calculate_min_free_kbytes(void);
> extern int __meminit init_per_zone_wmark_min(void);
> extern void mem_init(void);
> extern void __init mmap_init(void);
> -extern void show_mem(unsigned int flags, nodemask_t *nodemask, gfp_t gfp_mask);
> +
> +extern void __show_mem(unsigned int flags, nodemask_t *nodemask, int max_zone_idx);
> +static inline void show_mem(unsigned int flags, nodemask_t *nodemask)
> +{
> + __show_mem(flags, nodemask, MAX_NR_ZONES - 1);
> +}
> extern long si_mem_available(void);
> extern void si_meminfo(struct sysinfo * val);
> extern void si_meminfo_node(struct sysinfo *val, int nid);
> diff --git a/init/initramfs.c b/init/initramfs.c
> index ec966cb78363..18229cfe8906 100644
> --- a/init/initramfs.c
> +++ b/init/initramfs.c
> @@ -63,7 +63,7 @@ static void panic_show_mem(const char *fmt, ...)
> {
> va_list args;
>
> - show_mem(0, NULL, GFP_HIGHUSER_MOVABLE);
> + show_mem(0, NULL);
> va_start(args, fmt);
> panic(fmt, args);
> va_end(args);
> diff --git a/kernel/panic.c b/kernel/panic.c
> index ba5f7691d15c..a3308af28a21 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -187,7 +187,7 @@ static void panic_print_sys_info(bool console_flush)
> show_state();
>
> if (panic_print & PANIC_PRINT_MEM_INFO)
> - show_mem(0, NULL, GFP_HIGHUSER_MOVABLE);
> + show_mem(0, NULL);
>
> if (panic_print & PANIC_PRINT_TIMER_INFO)
> sysrq_timer_list_show();
> diff --git a/lib/show_mem.c b/lib/show_mem.c
> index b97461a6c4bb..ade71096e241 100644
> --- a/lib/show_mem.c
> +++ b/lib/show_mem.c
> @@ -8,13 +8,13 @@
> #include <linux/mm.h>
> #include <linux/cma.h>
>
> -void show_mem(unsigned int filter, nodemask_t *nodemask, gfp_t gfp_mask)
> +void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
> {
> pg_data_t *pgdat;
> unsigned long total = 0, reserved = 0, highmem = 0;
>
> printk("Mem-Info:\n");
> - show_free_areas(filter, nodemask, gfp_mask);
> + show_free_areas(filter, nodemask, max_zone_idx);
>
> for_each_online_pgdat(pgdat) {
> int zoneid;
> diff --git a/mm/nommu.c b/mm/nommu.c
> index 46cff4a51fa0..9d7afc2d959e 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -1047,7 +1047,7 @@ static int do_mmap_private(struct vm_area_struct *vma,
> enomem:
> pr_err("Allocation of length %lu from process %d (%s) failed\n",
> len, current->pid, current->comm);
> - show_free_areas(0, NULL, GFP_KERNEL);
> + show_free_areas(0, NULL);
> return -ENOMEM;
> }
>
> @@ -1270,13 +1270,13 @@ unsigned long do_mmap(struct file *file,
> kmem_cache_free(vm_region_jar, region);
> pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
> len, current->pid);
> - show_free_areas(0, NULL, GFP_KERNEL);
> + show_free_areas(0, NULL);
> return -ENOMEM;
>
> error_getting_region:
> pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
> len, current->pid);
> - show_free_areas(0, NULL, GFP_KERNEL);
> + show_free_areas(0, NULL);
> return -ENOMEM;
> }
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index ffeaad3b348d..94804504be9c 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -461,7 +461,7 @@ static void dump_header(struct oom_control *oc, struct task_struct *p)
> if (is_memcg_oom(oc))
> mem_cgroup_print_oom_meminfo(oc->memcg);
> else {
> - show_mem(SHOW_MEM_FILTER_NODES, oc->nodemask, oc->gfp_mask);
> + __show_mem(SHOW_MEM_FILTER_NODES, oc->nodemask, gfp_zone(oc->gfp_mask));
> if (should_dump_unreclaim_slab())
> dump_unreclaimable_slab();
> }
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 208e3f8b38f8..110a16ea848a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -4248,7 +4248,7 @@ static void warn_alloc_show_mem(gfp_t gfp_mask, nodemask_t *nodemask)
> if (!in_task() || !(gfp_mask & __GFP_DIRECT_RECLAIM))
> filter &= ~SHOW_MEM_FILTER_NODES;
>
> - show_mem(filter, nodemask, gfp_mask);
> + __show_mem(filter, nodemask, gfp_zone(gfp_mask));
> }
>
> void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
> @@ -5944,10 +5944,9 @@ static bool node_has_managed_zones(pg_data_t *pgdat, int max_zone_idx)
> * SHOW_MEM_FILTER_NODES: suppress nodes that are not allowed by current's
> * cpuset.
> */
> -void show_free_areas(unsigned int filter, nodemask_t *nodemask, gfp_t gfp_mask)
> +void __show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
> {
> unsigned long free_pcp = 0;
> - int max_zone_idx = gfp_zone(gfp_mask);
> int cpu;
> struct zone *zone;
> pg_data_t *pgdat;
Powered by blists - more mailing lists