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    SubjectRe: [PATCH] drivers: base: power: Fix GFP_KERNEL in spinlock context
    On Tue 2017-12-12 15:58:00, Geert Uytterhoeven wrote:
    > Hi Shrikant,
    >
    > On Tue, Dec 12, 2017 at 2:45 PM, <shrikant.maurya@techveda.org> wrote:
    > > From: Shrikant Maurya <shrikant.maurya@techveda.org>
    > >
    > > As reported by Jia-Ju Bai (https://lkml.org/lkml/2017/12/11/872):
    > > API's are using GFP_KERNEL to allocate memory which may sleep.
    > >
    > > To ensure atomicity such allocations must be avoided in critical
    > > sections under spinlock.
    > > Fixed by replacing GFP_KERNEL to GFP_ATOMIC.
    > >
    > > Reported-by: Jia-Ju Bai <baijiaju1990@gmail.com>
    > > Signed-off-by: Shrikant Maurya <shrikant.maurya@techveda.org>
    > > Signed-off-by: Suniel Mahesh <sunil.m@techveda.org>
    > > Signed-off-by: Raghu Bharadwaj <raghu@techveda.org>
    > > Signed-off-by: Karthik Tummala <karthik@techveda.org>
    >
    > Can't the call to device_init_wakeup() in isp116x_start() just be moved
    > below the spinlock release?
    >
    > > --- a/drivers/base/power/wakeup.c
    > > +++ b/drivers/base/power/wakeup.c
    > > @@ -92,11 +92,11 @@ struct wakeup_source *wakeup_source_create(const char *name)
    > > {
    > > struct wakeup_source *ws;
    > >
    > > - ws = kmalloc(sizeof(*ws), GFP_KERNEL);
    > > + ws = kmalloc(sizeof(*ws), GFP_ATOMIC);
    >
    > With GFP_ATOMIC, allocation failure is much more likely to occur.
    > So IMHO it's better to fix the isp116x, than to impose this burden on
    > every user.
    >
    > > if (!ws)
    > > return NULL;
    > >
    > > - wakeup_source_prepare(ws, name ? kstrdup_const(name, GFP_KERNEL) : NULL);
    > > + wakeup_source_prepare(ws, name ? kstrdup_const(name, GFP_ATOMIC) : NULL);
    > > return ws;

    NAK. This will silently replace name with NULL if memory is low.

    Pavel
    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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