On Thu, 2017-11-09 at 11:05 +0100, Michal Hocko wrote: > On Tue 07-11-17 08:03:27, Joe Perches wrote: > > On Tue, 2017-11-07 at 16:43 +0100, Michal Hocko wrote: > > > On Tue 07-11-17 07:34:25, Joe Perches wrote: > > > > [] > > > > I believe, but have not tested, that using a specific width > > > > as an argument to %*pb[l] will constrain the number of > > > > spaces before the '(null)' output in any NULL pointer use. > > > > > > > > So how about a #define like > > > > > > > > /* > > > > * nodemask_pr_args is only used with a "%*pb[l]" format for a nodemask. > > > > * A NULL nodemask uses 6 to emit "(null)" without leading spaces. > > > > */ > > > > #define nodemask_pr_args(maskp) \ > > > > (maskp) ? MAX_NUMNODES : 6, \ > > > > (maskp) ? (maskp)->bits : NULL > > > > > > Why not -1 then? > > > > I believe it's the field width and not the precision that > > needs to be set. > > But the first of the two arguments is the field with specifier, not the > precision. /me confused... > > Anyway, the following works as expected when printing the OOM report: > [ 47.005321] mem_eater invoked oom-killer: gfp_mask=0x14280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=(null), order=0, oom_score_adj=0 > [ 47.007183] mem_eater cpuset=/ mems_allowed=0-1 > [ 47.007829] CPU: 3 PID: 3223 Comm: mem_eater Tainted: G W 4.13.0-pr1-dirty #11 > > I hope I haven't overlooked anything Hey Michal. Seems right. The bit I overlooked was that the field width is overridden if the output is longer so 0 works perfectly well. Thanks. If it's useful, Acked-by: Joe Perches <joe@xxxxxxxxxxx> cheers, Joe > --- > From 35aa7742d35d29af88c66dd5e6f8f5d62215f5fd Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@xxxxxxxx> > Date: Thu, 9 Nov 2017 10:58:41 +0100 > Subject: [PATCH] mm: simplify nodemask printing > > alloc_warn and dump_header have to explicitly handle NULL nodemask which > forces both paths to use pr_cont. We can do better. printk already > handles NULL pointers properly so all what we need is to teach > nodemask_pr_args to handle NULL nodemask carefully. This allows > simplification of both alloc_warn and dump_header and get rid of pr_cont > altogether. > > This patch has been motivated by patch from Joe Perches > http://lkml.kernel.org/r/b31236dfe3fc924054fd7842bde678e71d193638.1509991345.git.joe@xxxxxxxxxxx > > Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> > --- > include/linux/nodemask.h | 2 +- > mm/oom_kill.c | 12 ++++-------- > mm/page_alloc.c | 12 +++--------- > 3 files changed, 8 insertions(+), 18 deletions(-) > > diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h > index cf0b91c3ec12..5d3cc67207ed 100644 > --- a/include/linux/nodemask.h > +++ b/include/linux/nodemask.h > @@ -103,7 +103,7 @@ extern nodemask_t _unused_nodemask_arg_; > * > * Can be used to provide arguments for '%*pb[l]' when printing a nodemask. > */ > -#define nodemask_pr_args(maskp) MAX_NUMNODES, (maskp)->bits > +#define nodemask_pr_args(maskp) (maskp) ? MAX_NUMNODES : 0, (maskp) ? (maskp)->bits : NULL > > /* > * The inline keyword gives the compiler room to decide to inline, or > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 8dd0e088189b..606213a81ceb 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -426,14 +426,10 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask) > > static void dump_header(struct oom_control *oc, struct task_struct *p) > { > - pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=", > - current->comm, oc->gfp_mask, &oc->gfp_mask); > - if (oc->nodemask) > - pr_cont("%*pbl", nodemask_pr_args(oc->nodemask)); > - else > - pr_cont("(null)"); > - pr_cont(", order=%d, oom_score_adj=%hd\n", > - oc->order, current->signal->oom_score_adj); > + pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), nodemask=%*pbl, order=%d, oom_score_adj=%hd\n", > + current->comm, oc->gfp_mask, &oc->gfp_mask, > + nodemask_pr_args(oc->nodemask), oc->order, > + current->signal->oom_score_adj); > if (!IS_ENABLED(CONFIG_COMPACTION) && oc->order) > pr_warn("COMPACTION is disabled!!!\n"); > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d755434aee94..457e43ed4c10 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3281,20 +3281,14 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...) > if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs)) > return; > > - pr_warn("%s: ", current->comm); > - > va_start(args, fmt); > vaf.fmt = fmt; > vaf.va = &args; > - pr_cont("%pV", &vaf); > + pr_warn("%s: %pV, mode:%#x(%pGg), nodemask=%*pbl\n", > + current->comm, &vaf, gfp_mask, &gfp_mask, > + nodemask_pr_args(nodemask)); > va_end(args); > > - pr_cont(", mode:%#x(%pGg), nodemask=", gfp_mask, &gfp_mask); > - if (nodemask) > - pr_cont("%*pbl\n", nodemask_pr_args(nodemask)); > - else > - pr_cont("(null)\n"); > - > cpuset_print_current_mems_allowed(); > > dump_stack(); > -- > 2.14.2 > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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